Fourth Amendment traffic stops1977434 U.S. 106
Mimms
A routine expired-plate stop became a major Fourth Amendment rule: police may order a driver out of a lawfully stopped car, but a frisk still needs a weapon-safety justification.
Cases
Published case studies for legal education and field-ready context.
Evidence Procedure1988100 L. Ed. 2d 30
California
For officers and detectives, California v. Greenwood supports the use of curbside trash pulls as an investigative technique under the federal Fourth Amendment. If garbage has been placed out for collection in an area accessible to the public and outside the home’s curtilage, officers generally do not need a warrant to seize and search it.
Evidence Procedure198482 L. Ed. 2d 599
Segura
For police officers and detectives, Segura v. United States is an important reminder that a valid warrant can preserve evidence only when the warrant is truly independent of any earlier mistake. If officers enter too soon without a warrant, they risk suppression of anything discovered during that entry.
Evidence Procedure197649 L. Ed. 2d 1046
United States
United States v. Janis: for officers, the first lesson is that Fourth Amendment rules still control searches and seizures. United States et al.
Evidence Procedure198376 L. Ed. 2d 527
Illinois
Illinois v. Gates is a core warrant case for officers because it confirms that probable cause is based on the whole picture. A strong affidavit should explain why, taken together, the facts create a fair probability that evidence will be found at the location.
Evidence Procedure198273 L. Ed. 2d 202
United States
United States v. Johnson matters to police because it shows that a constitutional rule can affect cases already in the pipeline, not just future arrests. If officers made a warrantless and nonconsensual home entry for a routine felony arrest before Payton, and the case was still on direct review when Payton was decided, the government could not simply say the arrest was valid because it occurred before Payton.
Evidence Procedure1989106 L. Ed. 2d 166
Duckworth
For officers and detectives, Duckworth v. Eagan is a reminder that Miranda warnings do not have to be word-for-word identical to the language in Miranda v. Arizona. What matters is whether the suspect is clearly told the substance of the rights: the right to remain silent, the possible use of statements in court, the right to counsel before and during questioning, and the right to appointed counsel if the suspect cannot afford one.
Evidence Procedure1990109 L. Ed. 2d 13
New York
For officers, detectives, and supervisors, New York v. Harris should not be read as permission to enter a home without a warrant whenever probable cause exists. Payton remains the controlling rule: absent valid consent or exigent circumstances, police generally need an arrest warrant before crossing the threshold of a suspect’s home to make an arrest.
Evidence Procedure1993123 L. Ed. 2d 407
Withrow
Withrow v. Williams does not change what officers must do during custodial interrogation. The basic Miranda rules remain the same: before custodial interrogation, give the required warnings; obtain a valid waiver before questioning; stop or adjust questioning when the suspect invokes the right to remain silent or the right to counsel; and avoid coercive tactics that could create separate voluntariness problems.
Evidence Procedure2012181 L. Ed. 2d 694
Perry
For officers, detectives, and supervisors, Perry v. New Hampshire draws an important but limited constitutional line. If a witness makes an identification under circumstances the police did not arrange, federal due process does not automatically require suppression just because the situation was suggestive.
Evidence Procedure198482 L. Ed. 2d 778
Immigration & Naturalization Service
For officers, the key takeaway is narrow but important: Immigration & Naturalization Service v. Lopez-Mendoza is about civil deportation proceedings, not ordinary criminal prosecutions. It should not be read as permission to ignore the Fourth Amendment.
Evidence Procedure198481 L. Ed. 2d 377
Nix
Nix v. Williams is important for officers because it explains why courts sometimes admit evidence even when a defendant claims there was a constitutional problem with the search. If the evidence would have been found through a lawful arrest, search incident to arrest, inventory, booking process, or other legitimate procedure, suppression may not be required.
Evidence Procedure1990107 L. Ed. 2d 676
James
For officers, detectives, and supervisors, James v. Illinois reinforces a simple point: evidence obtained in violation of the Constitution may be lost for more than just the prosecution’s main case. It also may be unavailable to impeach defense witnesses.
Evidence Procedure2010177 L. Ed. 2d 894
McDonald
McDonald v. City of Chicago: mcDonald matters to police because it means local firearm enforcement must account for the Second Amendment. A city ordinance is not insulated from constitutional review simply because it is local.
Evidence Procedure2006165 L. Ed. 2d 557
Sanchez-Llamas
Sanchez-Llamas v. Oregon: for police officers, the safest and most professional practice is to ask about foreign nationality when appropriate after arrest or detention and to give consular-notification advisements when the person is a foreign national. If the person asks for the consulate to be notified, the agency should follow its procedures for making that notification.
Miranda Interrogation1990110 L. Ed. 2d 243
Illinois
For officers and detectives, Illinois v. Perkins means that Miranda warnings are not required simply because a suspect is in jail if the suspect does not know he is talking to law enforcement. An undercover officer or agent posing as an inmate may speak with an incarcerated suspect, and the suspect’s statements are not excluded under Miranda solely because no warnings were given.
Miranda Interrogation1994129 L. Ed. 2d 362
Davis
For officers and detectives, Davis v. United States creates an important distinction between a clear request for a lawyer and an uncertain comment about a lawyer. If a suspect says something direct like “I want a lawyer,” “I want an attorney,” or “I will not talk without a lawyer,” questioning must stop unless counsel is provided or the suspect later reinitiates communication under the applicable rules.
Miranda Interrogation1994128 L. Ed. 2d 293
Stansbury
Stansbury v. California is a reminder that Miranda custody is judged from the outside, not from inside the officer’s head. What matters is what a reasonable person in the interviewee’s position would understand from the circumstances.
Miranda Interrogation1988485 U.S. 922
Patterson
Patterson v. United States: for police officers, Patterson is a cautionary case rather than a green light. The Supreme Court did not say that physical evidence found after Miranda-defective questioning is automatically usable.
Miranda Interrogation1988102 L. Ed. 2d 172
Pennsylvania
Pennsylvania v. Bruder reinforces that officers generally may conduct ordinary roadside DUI investigations without first giving Miranda warnings. During a typical traffic stop, an officer may make observations, request license and registration, ask basic investigative questions, and continue the roadside investigation without automatically converting the encounter into Miranda custody.
Miranda Interrogation1995133 L. Ed. 2d 383
Thompson
For officers and detectives, Thompson v. Keohane, Warden, et al. reinforces that Miranda custody is not controlled by labels alone.
Miranda Interrogation2000147 L. Ed. 2d 405
Dickerson
Dickerson v. United States confirms that officers should continue treating Miranda as a constitutional requirement during custodial interrogation. If a suspect is in custody and officers want to ask questions reasonably likely to produce incriminating responses, the safer and legally required practice is to give the Miranda warnings before questioning.
Miranda Interrogation2002153 L. Ed. 2d 47
McKune
McKune v. Lile: mcKune, Warden, et al. v. Lile does not give officers a general license to pressure inmates or suspects into confessing.
Miranda Interrogation2009173 L. Ed. 2d 955
Montejo
For officers and detectives, Montejo v. Louisiana means that appointment of counsel after a first court appearance does not always prohibit police from initiating a later custodial interview. If the suspect is properly Mirandized and chooses to waive those rights, the Sixth Amendment does not automatically suppress the statement merely because counsel has been appointed.
Miranda Interrogation2009173 L. Ed. 2d 801
Kansas
Kansas v. Ventris should not be read as permission to place informants near charged defendants for the purpose of getting around defense counsel. Once formal charges have been filed and the Sixth Amendment right to counsel has attached, officers and agents must not deliberately elicit statements from the accused outside the presence of counsel or without a valid waiver.
Miranda Interrogation2003155 L. Ed. 2d 814
Kaupp
Kaupp v. Texas is a warning that “bringing someone in for questioning” can legally become an arrest based on what officers do, not what they call it. If officers wake a suspect at home, control his movement, handcuff him, place him in a patrol car, and transport him to another location, a court is very likely to view that as an arrest.
Miranda Interrogation2009173 L. Ed. 2d 443
Corley
For federal officers, and for state or local officers working closely with federal agents, Corley v. United States is a reminder that Miranda warnings are not the only timing concern during interrogation. Advising a suspect of rights and obtaining a waiver are important, but they do not automatically solve a prompt-presentment problem.
Miranda Interrogation2006165 L. Ed. 2d 224
Davis
Davis v. Washington matters because it affects how courts view statements gathered during emergency calls and on-scene domestic violence investigations. When officers or dispatchers are trying to determine whether there is an immediate threat, where the suspect is, whether anyone is injured, and what response is needed, the resulting statements are more likely to be viewed as non-testimonial.
Miranda Interrogation2004158 L. Ed. 2d 938
Yarborough
Yarborough v. Alvarado: yarborough, Warden v. Alvarado is a reminder that a station-house interview is not automatically “custody” for Miranda purposes. If a person voluntarily comes to the station, is not restrained, is not threatened with arrest, and leaves afterward, those facts can support a finding that Miranda warnings were not required.
Miranda Interrogation2013186 L. Ed. 2d 376
Salinas
For officers and detectives, Salinas v. Texas matters most during voluntary, noncustodial interviews. If a person is not in custody and voluntarily speaks with police, the Constitution does not automatically bar the government from later using the person’s selective silence in response to a question, at least where the person did not clearly invoke the Fifth Amendment.
Miranda Interrogation2004157 L. Ed. 2d 1016
Fellers
Fellers v. United States is an important reminder that Miranda and the Sixth Amendment are related but not identical. Miranda focuses on custodial interrogation.
Miranda Interrogation2001149 L. Ed. 2d 321
Texas
Texas v. Cobb is important for officers and detectives because it confirms that the Sixth Amendment right to counsel is offense-specific. If a person has been charged and has counsel on one offense, that does not automatically prevent officers from questioning the person about a separate, uncharged offense.
Miranda Interrogation2001532 U.S. 1034
Bridgers
For officers, Bridgers v. Texas is a reminder that Miranda wording matters. A warning that starts correctly with “You have the right to remain silent” is only part of the requirement.
Miranda Interrogation2011180 L. Ed. 2d 310
J. D. B.
For officers and detectives, J. D. B. v. North Carolina means that juvenile interviews require careful custody analysis before questioning begins. If the subject is a child, especially a young teenager, officers should not evaluate the situation exactly as if the subject were an adult.
Miranda Interrogation2004159 L. Ed. 2d 643
Missouri
For police officers, Missouri v. Seibert is a warning against using Miranda as an afterthought. If a suspect is in custody and officers are going to interrogate, Miranda warnings should be given before questioning begins.
Miranda Interrogation2010175 L. Ed. 2d 1009
Florida
For police officers and detectives, Florida v. Powell confirms that courts look at the Miranda warning as a whole. A warning does not automatically fail just because it uses wording different from the standard Miranda phrasing.
Miranda Interrogation2011181 L. Ed. 2d 328
Bobby
Bobby v. Dixon: for officers and detectives, Bobby, Warden v. Dixon reinforces a basic point: Miranda warnings are required before custodial interrogation. If a person is not in custody, Miranda warnings are not constitutionally required, although giving clear advisements may still be the safer practice in serious investigations.
Miranda Interrogation2004159 L. Ed. 2d 667
United States
United States v. Patane does not give officers permission to ignore Miranda. Officers should still give complete Miranda warnings before custodial interrogation when they want to question a suspect and preserve the suspect’s statements for use in court.
Miranda Interrogation2010175 L. Ed. 2d 1045
Maryland
For police officers and detectives, Maryland v. Shatzer is an important Miranda case because it gives a concrete time rule. If a suspect in custodial interrogation asks for a lawyer, stop questioning immediately.
Miranda Interrogation2012182 L. Ed. 2d 17
Howes
Howes v. Fields: howes, Warden v. Fields is important for officers and detectives who interview inmates about crimes that are separate from the sentence the inmate is already serving. The case teaches that an inmate is not automatically in Miranda custody just because officers remove him from his cell or housing unit and question him in another room about an outside offense.
Miranda Interrogation2022597 U.S. 134
Vega
Vega v. Tekoh does not eliminate Miranda. Officers still need to understand and follow Miranda when conducting custodial interrogation.
Pursuits Vehicle Operations2007489 F. Supp. 2d 111
Therrien
Therrien v. Town of Jay: officers, supervisors, and trainers should not rely on the limited excerpt as authority for any specific pursuit tactic, emergency driving decision, or municipal liability rule. The available material does not say what the officer did, what the plaintiff alleged, or how the court evaluated the conduct.
Pursuits Vehicle Operations2019918 F.3d 1109
Lindsey
Lindsey v. Hyler is important for officers because it separates constitutional liability from policy, training, and tactical judgment. The court did not say every pursuit for a minor infraction is good policing.
Pursuits Vehicle Operations201075 A.D.3d 415
People
People v. Jones: for police work, the supplied material is not enough to support an operational takeaway about pursuits or vehicle operations. Officers should not rely on this excerpt alone to justify a pursuit, stop, arrest, search, charge, or report language.
Pursuits Vehicle Operations20112011 Ohio 1832
State
State v. Wynn is important for officers because it reinforces the distinction between pursuit and seizure. A suspect who runs from police has not necessarily been seized simply because officers are chasing him or ordering him to stop.
Pursuits Vehicle Operations2023213 N.E.3d 808
State
State v. Thornton supports the idea that officers may approach people in public places to investigate what they observe, including possible open-container violations, especially in an area with documented crime concerns. Officers should remember, however, that the high-crime nature of an area does not stand alone.
Pursuits Vehicle Operations20252025 NY Slip Op 02144
People
People v. Cleveland: based on the supplied material alone, the safest training takeaway is a documentation and legal-research point: officers, supervisors, and instructors should not rely on the case name and citation by themselves to change pursuit, stop, or vehicle-operation practices. The full Court of Appeals opinion must be reviewed to identify the facts, the legal issue, the holding, and the limits of the ruling.
Pursuits Vehicle Operations2017286 F. Supp. 3d 1226
Roybal-Mack
Roybal-Mack v. N.M. Dep't of Pub. Safety: this case reinforces that federal courts distinguish between bad outcomes and constitutional violations. A fatal crash connected to a pursuit is a serious event, but the plaintiff still must prove that the officer’s conduct crossed the constitutional line.
Pursuits Vehicle Operations2019920 F.3d 1168
United States
United States v. Alvin Houston is useful for officers because it reinforces that a command to stop does not become a Fourth Amendment seizure unless the person submits or officers physically restrain the person. If a person keeps running after an officer yells “wait” or “stop,” the seizure has not yet occurred under the Fourth Amendment.
Pursuits Vehicle Operations2017211 So. 3d 894
State of Florida
For Florida officers, State of Florida v. Christopher Markus is a cautionary home-entry case. If the pursuit involves a misdemeanor, do not assume that crossing the threshold is lawful just because the suspect went inside while you were trying to stop or arrest him.
Pursuits Vehicle Operations20192019 NY Slip Op 1673
People
For officers, the main takeaway from the available material is caution in how the case is used. People v. Bilal appears to be relevant to vehicle operations or pursuit-related policing, but the provided source does not give enough detail to turn it into a training rule.
Pursuits Vehicle Operations20162016 Ohio 7327
State
State v. Roberts: this case is not a vehicle pursuit or emergency-driving case based on the source text provided. Its practical value for police work is mainly about evidence development, documentation, and how courts review the totality of proof after a bench trial.
Pursuits Vehicle Operations2019377 F. Supp. 3d 1272
United States
United States v. Silcott: for officers, the confirmed takeaway is limited: suppression motions are often decided based on the specific facts developed at an evidentiary hearing. Reports, testimony, video, dispatch records, and the sequence of officer observations can become critical when a defendant later challenges the evidence.
Pursuits Vehicle Operations2025138 F.4th 822
Salinas
Salinas v. City of Houston is a pursuit and vehicle-shooting case, but its lessons are narrower than a general rule about all pursuits or all post-crash encounters. The Fifth Circuit’s decision was tied closely to the facts captured on body-worn camera: the officers had vehicle information before the stop, activated their lights, observed a failure to stop, engaged in a pursuit, confronted the driver after a crash, gave many commands, and fired only after repeated reaching movements inside the vehicle.
Pursuits Vehicle Operations2019203 A.3d 272
Commonwealth
For officers, Commonwealth v. Dunham reinforces that a valid traffic stop lawfully detains everyone in the vehicle for purposes of the stop. Officers do not need a separate individualized basis to treat a passenger as seized at the moment a lawful traffic stop is initiated.
Pursuits Vehicle Operations202380 F.4th 872
Clara Cheeks
For officers, the main lesson from Clara Cheeks v. Mark Jakob is that the medical-aid duty after a pursuit-related crash can become a constitutional issue, not just a policy or negligence issue, when police action allegedly causes the crash. The decision is especially relevant to PIT maneuvers or other intentional vehicle-contact tactics used to end a pursuit.
Pursuits Vehicle Operations20212021 Ohio 650
State
State v. Kimes is useful for officers because it recognizes a narrow difference between rummaging through a phone and taking a limited step to identify the owner of a lost or unattended device. The court did not say that officers may freely search a found phone.
Pursuits Vehicle Operations2022197 N.E.3d 1040
Westlake
Westlake v. Roberts is an important reminder that the threshold of a home is a constitutional line. Even when an officer has lawfully initiated a traffic stop, and even when a suspect disobeys commands and runs inside, entry into the home requires either a warrant, consent, or a recognized exception to the warrant requirement.
Use Of Force2019931 F.3d 672
Z. J.
Z. J. v. Kansas City Brd of Police Comm: for officers executing warrants, this case is a strong warning that a flash-bang grenade is not just a routine entry tool. It is a significant use of force that must be tied to the actual risks known at the time.
Pursuits Vehicle Operations1988100 L. Ed. 2d 565
Michigan
Michigan v. Chesternut gives officers room to observe and follow a person who runs at the sight of police, at least where the officers do not use commands, emergency equipment, weapons, blocking tactics, or other show-of-authority measures that would communicate a detention. Officers may follow to see where the person goes and may act on evidence that comes into plain view before a seizure occurs.
Use Of Force202389 F.4th 614
Allen Bloodworth, II
Allen Bloodworth, II v. Kansas City Board of Police Commissioners: the only police-work implication that can be drawn from the supplied material is that this is an Eighth Circuit use-of-force case and may be relevant for officers working in jurisdictions governed by Eighth Circuit precedent. The specific lesson for officers needs source verification from the full opinion.
Use Of Force202235 F.4th 1111
N.S.
N.S. v. Kansas City Board of Police is a reminder that courts separate bad outcomes from constitutional violations. An injury during a police operation is important and may trigger reporting, investigation, supervision review, policy analysis, and possibly state-law claims.
Use Of Force2018885 F.3d 639
Charles Byrd
Charles Byrd v. Phoenix Police Department: for officers, the key takeaway is that an arrest-related conviction does not automatically end later civil litigation over force. Even if a subject is convicted of resisting arrest, assaulting an officer, or another offense from the same incident, a court may still allow an excessive-force claim if the alleged force could have occurred separately from the criminal act or after the subject was under control.
Use Of Force2019935 F.3d 651
Rudley
The main police-work lesson that can be drawn from the limited source material is a cautionary one: use-of-force cases are fact-specific, and officers, supervisors, and trainers should not rely on a case citation without reading the actual facts and holding. Rudley v. Little Rock Police Dep't may be important to Eighth Circuit use-of-force law, but the supplied material is not enough to identify its concrete rule.
Use Of Force202227 F.4th 1148
Linda Moser
For officers, Linda Moser v. Etowah Police Dep't reinforces that constitutional use-of-force analysis starts with identifying who the officer was trying to stop, seize, or restrain. If force is intentionally used to arrest or control a person, the reasonableness of that force will be judged under the Fourth Amendment.
Use Of Force2020980 F.3d 231
Frost
Frost v. New York City Police Department reinforces a basic Fourth Amendment lesson: the authority to arrest does not automatically justify any amount of force. Officers should be able to explain why the force used was necessary based on the person’s conduct, threat level, resistance, and the operational realities at the scene.
Use Of Force2021193 A.D.3d 1346
Snow
Because the source material does not provide the facts or holding, this case should not be used as a training example for a specific use-of-force rule without checking the actual opinion. For police work, the only grounded takeaway from the supplied material is that Snow v. Rochester Police Officer Christopher Schreier is a New York appellate case involving police use of force.
Use Of Force202254 F.4th 1232
Mahdi
Based only on the provided metadata, Mahdi v. Salt Lake Police Department should be treated as a case requiring further review before it is used in training or policy discussions. Officers should not rely on this summary as authority for a specific tactic because the source material does not identify the force used, the subject’s conduct, the level of threat, or the court’s reasoning.
Use Of Force1945325 U.S. 91
Screws
For police officers, Screws v. United States is an early and important reminder that official authority does not shield an officer who uses force as punishment, revenge, intimidation, or any other unlawful purpose. When an officer acts under color of law, the officer is not acting as a private citizen.
Use Of Force198168 L. Ed. 2d 420
Parratt
Parratt v. Taylor is not a use-of-force case. It does not decide when officers may use force, seize a person, or conduct a search.
Use Of Force197751 L. Ed. 2d 711
Ingraham
Ingraham v. Wright is not a police arrest or detention force case, and officers should not read it as authority to use force as punishment. The case dealt with school discipline, not law enforcement force.
Use Of Force2003538 U.S. 1
Ben Chavez
Ben Chavez v. Oliverio Martinez is important because it separates two issues that are often blended together in the field: whether a statement can be used in court, and whether the act of questioning creates civil liability. The Court said the Fifth Amendment self-incrimination problem arises when compelled statements are used in a criminal case, not simply because an officer asked questions without Miranda warnings.
Use Of Force198689 L. Ed. 2d 452
Pembaur
Pembaur v. City of Cincinnati is mainly a municipal-liability case, not a case that rewrites search-warrant or use-of-force rules. Its lesson for officers is that a one-time order from the right official can have major legal consequences for the agency.
Use Of Force198585 L. Ed. 2d 791
City of Oklahoma
City of Oklahoma v. Tuttle: for patrol officers, City of Oklahoma City v. Tuttle is mainly a municipal-liability case, not a new use-of-force standard. It does not say that an officer’s use of force is lawful just because it happened only once.
Use Of Force1996135 L. Ed. 2d 392
Koon
Koon v. United States should not be read as approval of the force used against Rodney King. The officers’ federal civil-rights convictions were not erased by this decision.
Use Of Force1998140 L. Ed. 2d 1043
County of Sacramento
County of Sacramento v. Lewis is an important use-of-force and pursuit case because it recognizes the realities of fast-moving police decisions. The Supreme Court did not say that pursuits are risk-free or that officers have unlimited authority to chase.
Use Of Force2003155 L. Ed. 2d 984
Chavez
Chavez v. Martinez is important for officers because it separates two related but different concepts: questioning someone without Miranda warnings and violating the Fifth Amendment Self-Incrimination Clause. If officers question a suspect without Miranda warnings, the likely consequence in a criminal case is that the statement may be excluded from evidence.
Use Of Force2001149 L. Ed. 2d 549
Atwater
Atwater v. City of Lago Vista gives officers a constitutional baseline: if you have probable cause that a person committed a criminal offense in your presence, the Fourth Amendment generally allows a custodial arrest, even for a very minor misdemeanor. The case is especially important in traffic and low-level offense settings, where officers often must decide between a citation, warning, summons, or arrest.
Use Of Force1993126 L. Ed. 2d 490
United States
For police officers, detectives, and supervisors, United States v. James Daniel Good Real Property is a reminder that civil forfeiture involving houses, land, or other real property has constitutional limits. Even when officers have strong evidence that a property was used in drug activity, the government normally cannot simply take control of that real property without giving the owner notice and a chance to be heard.
Use Of Force2017582 U.S. 120
Ziglar
For federal officers, Ziglar v. Abbasi is important because it limits when a person can sue individual federal officials for money damages directly under the Constitution. If a claim arises in a new context, especially one involving national security, immigration, detention policy, or high-level operational decisions, courts will be reluctant to create a new Bivens remedy unless Congress has clearly provided for it.
Use Of Force2011179 L. Ed. 2d 1118
Camreta
Camreta v. Greene Ex Rel. S. G.: camreta v. Greene Ex Rel. <dot> <dot> is not a use-of-force case in the ordinary sense.
Use Of Force1994127 L. Ed. 2d 114
Albright
Albright v. Oliver is not a use-of-force case, and it does not set rules for how much physical force officers may use. Its value for officers is in understanding how courts classify constitutional claims arising from arrests and criminal charges.
Use Of Force2014188 L. Ed. 2d 1039
Wood
For police officers, Wood v. Moss is a reminder that crowd-control decisions near protected persons, public officials, or sensitive locations should be grounded in real security considerations. If one group is closer to a threat area, has better access to a protected person, or presents a different line-of-sight issue, officers may have a lawful basis to move that group even if the group is engaged in political speech.
Use Of Force2015575 U.S. 600
City and County of San Francisco
City and County of San Francisco v. Sheehan is important for officers responding to mental health crisis calls involving weapons. The case recognizes that mental illness is part of the total situation, but it does not eliminate the officer’s right to protect life when a person presents an immediate threat with a deadly weapon.
Use Of Force2004160 L. Ed. 2d 583
Brosseau
For officers, Brosseau v. Haugen is mainly a qualified-immunity case, not a broad use-of-force permission slip. The Supreme Court protected the officer from personal civil liability because the law at the time did not clearly establish that her specific action was unconstitutional.
Use Of Force2017582 U.S. 548
Hernandez
Hernandez v. Mesa: for officers, the most important operational lesson is that use-of-force decisions are judged based on the facts reasonably known to the officer at the moment force is used. Later-discovered information may matter for investigation or context, but it cannot normally be used to prove that an officer made a reasonable decision if the officer did not know it at the time.
Use Of Force2022596 U.S. 36
Thompson
Thompson v. Clark is not mainly a use-of-force case, even though it arose from a police response at a home and an arrest. Its main importance for police work is in the area of arrests, criminal complaints, and later civil litigation.
Use Of Force2021592 U.S. 306
Torres
For police officers, Torres v. Madrid means that an unsuccessful attempt to stop a person with intentional physical force can still count as a seizure. If an officer fires at a person to stop that person and the person is hit, the Fourth Amendment is implicated even if the person drives away, runs away, or is not immediately handcuffed.
Use Of Force2017580 U.S. 73
White
White v. Pauly is important for officers because it shows how courts analyze split-second force decisions and qualified immunity. The Supreme Court recognized that Officer White entered an already dangerous situation and had very little time to react.
Use Of Force2014188 L. Ed. 2d 895
Tolan
Tolan v. Cotton is a reminder that use-of-force cases often turn on small factual details. In a deadly force case, courts will look closely at what the officer saw, what the person did, the person’s position and movement, the distance involved, whether commands were given, whether the person appeared armed, and whether witnesses support or contradict the officer’s account.
Use Of Force2015576 U.S. 389
Kingsley
Kingsley v. Hendrickson matters most in custodial settings involving pretrial detainees, such as jails, holding facilities, and similar detention environments. The case does not say that officers cannot use force in jail.
Use Of Force2015577 U.S. 7
Mullenix
Mullenix v. Luna is important for officers because it shows how qualified immunity works in use-of-force cases, especially vehicle pursuit cases. The decision does not say that officers may freely shoot at fleeing vehicles.
Use Of Force2018584 U.S. 100
Kisela
For officers, Kisela v. Hughes reinforces that courts evaluate use-of-force decisions from the perspective of what officers reasonably knew at the time, not with the benefit of hindsight. Facts discovered later, such as whether the potential victim actually felt afraid, may matter in the broader case, but they do not control what the officer reasonably perceived in the moment if the officer did not know them.
Use Of Force2022596 U.S. 482
Egbert
For federal officers, especially those working in border, immigration, or national-security-related assignments, Egbert v. Boule makes it much harder for plaintiffs to bring new Bivens damages claims. The decision signals that courts will usually defer to Congress rather than create new personal-capacity damages remedies against federal officers.
Use Of Force2021595 U.S. 1
Rivas-Villegas
For officers, Rivas-Villegas v. Cortesluna is primarily a qualified-immunity case, not a broad approval of any particular control technique. The decision recognizes that officers may need to use brief physical control while securing a suspect, especially after a serious domestic-violence call involving a reported threat and a visible weapon.
Use Of Force2021595 U.S. 9
City of Tahlequah
For officers, City of Tahlequah v. Bond is mainly a qualified immunity case, not a use-of-force training manual. The Supreme Court did not say that every similar shooting is automatically lawful.
Use Of Force2019586 U.S. 38
City of Escondido
City of Escondido v. Emmons does not give officers a blanket rule allowing takedowns whenever they respond to a domestic violence call. It also does not say the force used was necessarily constitutional on the merits.
Use Of Force2025605 U.S. 73
Barnes
Barnes v. Felix is important because it reinforces that use-of-force decisions will be judged in context. Officers should expect that courts, agencies, and attorneys will examine not only the instant when force was used, but also the lead-up to that moment.
Searches Warrants198794 L. Ed. 2d 326
United States
United States v. Dunn gives officers a practical framework for evaluating rural property, farms, ranches, and properties with barns or outbuildings. The key point is that property lines and fences do not automatically define Fourth Amendment curtilage.
Searches Warrants1990108 L. Ed. 2d 222
United States
For officers and investigators, United States v. Verdugo-Urquidez is mainly a case about the reach of the Fourth Amendment outside the United States. It does not say that every overseas search by United States law enforcement is automatically proper.
Searches Warrants198168 L. Ed. 2d 38
Steagald
For police officers, Steagald v. United States is a key Fourth Amendment case on serving arrest warrants at third party residences. If officers have an arrest warrant for a suspect and believe the suspect is inside another person’s home, the safer constitutional practice is to obtain a search warrant for that residence before entering, unless valid consent or exigent circumstances are present.
Searches Warrants1994128 L. Ed. 2d 1
Powell
For officers, Powell v. Nevada reinforces the importance of the County of Riverside v. McLaughlin rule. After a warrantless arrest, the person arrested must receive a judicial determination of probable cause without unreasonable delay.
Searches Warrants1988101 L. Ed. 2d 472
Murray
Murray v. United States is an important warning for officers: do not treat a later warrant as a cure-all for an earlier unlawful entry. A search warrant obtained after an illegal entry may survive only if it is genuinely independent of that entry.
Searches Warrants1991114 L. Ed. 2d 619
California
California v. Acevedo gives officers a clearer rule for vehicle-container searches. When a container is in a vehicle and there is probable cause to believe that the container contains contraband or evidence, the Fourth Amendment does not require officers to obtain a warrant before opening that container.
Searches Warrants1999143 L. Ed. 2d 818
Wilson
For officers, Wilson v. Layne draws a clear line: lawful authority to enter a home under a warrant does not include authority to bring in outsiders who have no role in the warrant operation. If the person is not needed to help execute the warrant, identify evidence or a suspect, ensure safety, provide technical assistance, or otherwise support a legitimate law enforcement objective, that person should not be inside the home during the operation.
Searches Warrants1995131 L. Ed. 2d 34
Arizona
Arizona v. Evans supports the principle that officers may generally rely on official warrant information that appears valid, especially when the record comes through normal law enforcement databases and there is no reason to suspect it is wrong. If an officer runs a person, receives a hit showing an active warrant, and acts reasonably on that information, evidence found during a lawful arrest process may not be suppressed simply because a court clerk failed to update the warrant status.
Searches Warrants198794 L. Ed. 2d 364
Illinois
Illinois v. Krull gives officers some protection when they act in good faith under a statute that appears valid at the time of the search. If a legislature has authorized a particular inspection or search procedure, and an officer reasonably follows that law, the evidence may not be suppressed simply because a court later strikes the statute down.
Searches Warrants198794 L. Ed. 2d 72
Maryland
Maryland v. Garrison is an important warrant case for officers because it recognizes that search warrants are often obtained and executed in real-world conditions where building layouts, apartment divisions, and occupancy details may not be obvious. The Fourth Amendment does not demand perfection.
Searches Warrants1990111 L. Ed. 2d 148
Illinois
Illinois v. Rodriguez is an important case for officers handling consent entries at homes, apartments, hotel rooms, and similar private spaces. The practical rule is that consent from a third party can be valid if the person has actual common authority, and it can also be valid if officers reasonably believe the person has that authority.
Searches Warrants1998141 L. Ed. 2d 344
Pennsylvania Bd. of Probation and Parole
For police officers and parole agents, Pennsylvania Bd. of Probation and Parole v. Scott means that evidence from a search that may have violated the Fourth Amendment is not necessarily excluded from a parole revocation hearing under the federal exclusionary rule.
Searches Warrants1997137 L. Ed. 2d 41
Maryland
Maryland v. Wilson gives officers a clear safety rule for lawful traffic stops: if the stop itself is valid, an officer may direct passengers to exit the vehicle. The officer does not need to first develop individualized suspicion that the passenger is armed, dangerous, or committing a crime before giving the exit order.
Searches Warrants1990110 L. Ed. 2d 112
Horton
Horton v. California is a key plain-view case for officers executing search warrants. If you are lawfully inside a location under a valid warrant and are searching in places where the warrant allows you to search, you do not have to ignore obvious evidence simply because it is not listed in the warrant.
Searches Warrants198797 L. Ed. 2d 258
California
For police officers, the key takeaway is restraint: California v. Rooney is not an operational green light. Because the Supreme Court dismissed the case without deciding the Fourth Amendment issue, officers and supervisors should not rely on it as authority for conducting a warrantless search or for bypassing established warrant requirements.
Searches Warrants2013186 L. Ed. 2d 1
Maryland
For officers, Maryland v. King supports DNA collection during booking when the arrest is lawful, the offense qualifies under the governing DNA statute, and the agency follows the required procedures. The case is strongest when the DNA swab is handled like an identification step in the booking process, similar in purpose to fingerprinting, photographing, and checking records.
Searches Warrants2001150 L. Ed. 2d 94
Kyllo
For police officers, Kyllo v. United States is a home-search technology case. If an investigative tool is used from outside a residence to learn information about conditions or activity inside the residence, officers should consider whether using that tool is itself a search requiring a warrant.
Searches Warrants2003157 L. Ed. 2d 769
Maryland
Maryland v. Pringle gives officers important guidance, but it should not be read as permission to automatically arrest every passenger any time contraband is found in a vehicle. The decision depends on the totality of the circumstances.
Searches Warrants197856 L. Ed. 2d 525
Zurcher
For officers and detectives, Zurcher v. Stanford Daily means that the Fourth Amendment allows evidence-based warrants, not only suspect-based warrants. If investigators have probable cause that evidence of a crime is located at a particular place, a warrant may be constitutionally valid even if the person or organization controlling that place is not believed to be involved in the crime.
Searches Warrants2012182 L. Ed. 2d 662
Filarsky
For police officers, detectives, and supervisors, Filarsky v. Delia is most important when outside personnel are brought into an official investigation or government operation. A city attorney, outside counsel, consultant, medical expert, forensic specialist, or other temporary government agent may be able to claim qualified immunity if sued for actions taken while assisting the government in an official function.
Searches Warrants1996135 L. Ed. 2d 1031
Pennsylvania
For police officers, Pennsylvania v. Labron is an important automobile-exception case. If officers have probable cause to believe a vehicle contains drugs, weapons, or other contraband, and the vehicle is readily mobile, the Fourth Amendment allows a warrantless search of the vehicle without an added exigency requirement.
Searches Warrants1999143 L. Ed. 2d 399
Conn
Conn v. Gabbert is most useful for officers as a reminder that executing a search warrant may temporarily interfere with a person’s job, business, or professional duties without automatically creating a separate Fourteenth Amendment violation. If officers lawfully execute a warrant, the fact that the search disrupts a lawyer, doctor, business owner, or other professional for a short time does not by itself mean the person has been constitutionally deprived of the right to work.
Searches Warrants2021594 U.S. 295
Lange
Lange v. California is an important reminder that the home is different. A person’s house, including an attached garage, receives the highest level of Fourth Amendment protection.
Searches Warrants1999142 L. Ed. 2d 373
Minnesota
Minnesota v. Carter is important for officers because it limits who can challenge a search or observation involving a residence. A suspect found inside someone else’s home is not automatically protected as if he lived there.
Searches Warrants1999143 L. Ed. 2d 748
Florida
For officers, Florida v. White supports a narrow but important rule: a warrant is not always required to seize a vehicle from a public parking lot or other public place when there is probable cause to believe the vehicle is itself subject to forfeiture because of its use in crime. The case does not mean that every vehicle connected to a suspect may be taken without a warrant.
Searches Warrants1999143 L. Ed. 2d 408
Wyoming
Wyoming v. Houghton is an important vehicle-search case for officers. If you have lawful probable cause to search a vehicle for drugs, weapons, or other contraband, you may search areas and containers in the vehicle where that evidence could reasonably be found.
Searches Warrants1999142 L. Ed. 2d 636
City of West Covina
For officers, City of West Covina v. Perkins means that due process focuses on notice of the seizure, not on giving legal advice. When police seize property under a warrant, they should make sure the owner or occupant receives reasonable notice that the property was taken.
Searches Warrants1999143 L. Ed. 2d 978
Hanlon
Hanlon v. Berger is a warning that the scope of a warrant matters. When a judge authorizes a search, the authorization is tied to the place, evidence, people, and law-enforcement purpose described in the warrant.
Searches Warrants2003538 U.S. 1
Inyo County, California
Inyo County, California v. Paiute-Shoshone Indians of the Bishop Community of the Bishop Colony: for officers, detectives, and supervisors, this case is important because it shows that searches involving tribal governments or tribal enterprises can raise issues beyond ordinary warrant practice. A state search warrant directed at records held by a tribal entity may trigger questions about tribal sovereignty, jurisdiction, and the proper legal process for obtaining the evidence.
Searches Warrants1999144 L. Ed. 2d 442
Maryland
For officers, Maryland v. Dyson is an important automobile-exception case. If you have probable cause that a vehicle contains drugs, weapons, or other evidence, and the vehicle is readily mobile, the Fourth Amendment does not require you to stop and get a warrant simply because there is time to do so.
Searches Warrants2006164 L. Ed. 2d 208
Georgia
Georgia v. Randolph matters most at the front door of a shared home. If one lawful occupant consents to a search, officers still need to pay attention to whether another lawful occupant is physically present and objecting.
Searches Warrants2015576 U.S. 409
Los Angeles
For officers, Los Angeles v. Patel is a reminder that required business records are not automatically open for immediate police inspection just because a local ordinance says they must be maintained. If a hotel employee voluntarily consents to show the registry, that is different.
Searches Warrants2009175 L. Ed. 2d 410
Michigan
Michigan v. Fisher is an important emergency entry case for patrol officers because it confirms that the law allows practical, safety-based decision-making when officers encounter signs of injury, violence, and possible danger inside a residence. For police work, the key point is that the emergency aid exception is based on what the facts would lead a reasonable officer to believe at the time.
Searches Warrants2011179 L. Ed. 2d 865
Kentucky
Kentucky v. King is an important case for drug investigations, apartment investigations, and knock-and-talk situations. It confirms that officers may lawfully approach a door, knock, and announce their presence.
Searches Warrants2018584 U.S. 586
Collins
Collins v. Virginia is a warning against treating every vehicle the same regardless of location. Probable cause that a car, truck, or motorcycle is stolen or contains evidence may support a vehicle search under the automobile exception, but it does not automatically authorize officers to walk into the protected area around a house to get to it.
Searches Warrants2002153 L. Ed. 2d 599
Kirk
For officers, the lesson of Kirk v. Louisiana is simple: do not treat probable cause as a passkey to a house. Probable cause may be enough for a warrantless arrest in a public place, but a home is different.
Searches Warrants2013185 L. Ed. 2d 696
Missouri
Missouri v. McNeely means that officers investigating impaired driving should not assume that every refusal automatically permits a warrantless blood draw. If the suspect does not consent, and no other recognized exception applies, the safer constitutional course is to obtain a search warrant before ordering a blood draw.
Searches Warrants2016579 U.S. 438
Birchfield
Birchfield v. North Dakota: for patrol officers, the main takeaway is that breath and blood tests must be treated differently. After a lawful DUI arrest, a breath test is generally the safer warrantless option under Birchfield because the Supreme Court approved breath testing as a search incident to arrest.
Searches Warrants2004157 L. Ed. 2d 1068
Groh
Groh v. Ramirez is a warrant-drafting case with direct consequences for officers. Before executing a warrant, especially one you prepared or reviewed, make sure the warrant identifies the place to be searched and the specific items, evidence, contraband, or persons to be seized.
Searches Warrants2014188 L. Ed. 2d 25
Fernandez
For officers, Fernandez v. California is important in shared-residence consent searches. If two people live in a residence and one is present and clearly objects to entry or search, officers generally cannot ignore that objection by relying on the other occupant’s consent while the objector remains physically present.
Searches Warrants2007167 L. Ed. 2d 974
Los Angeles County, California
Los Angeles County, California v. Rettele gives officers some breathing room during the first moments of a warrant execution. The Supreme Court recognized that officers entering a residence under a warrant often face uncertainty, limited information, and potential danger.
Searches Warrants2012182 L. Ed. 2d 47
Messerschmidt
Messerschmidt v. Millender is important for officers because it shows that getting a warrant matters, and getting meaningful review before submitting it matters too. When officers prepare a warrant, have it reviewed by supervisors or prosecutors, and present it to a neutral judge, those steps can strongly support the reasonableness of the officer’s actions if the warrant is later challenged.
Searches Warrants2006164 L. Ed. 2d 195
United States
United States v. Grubbs is important for controlled deliveries and other investigations where officers expect evidence to arrive at a location after the warrant is issued. Officers may seek an anticipatory warrant before the evidence is physically present, but the affidavit must give the judge a solid basis to find that the triggering event is likely to happen and that evidence will be present if it does.
Searches Warrants19616 L. Ed. 2d 1127
Marcus
For police officers, Marcus v. Search Warrant of Property is a warning against treating expressive materials like ordinary contraband. If the investigation involves books, magazines, newspapers, films, recordings, digital publications, or similar expressive content, officers should expect courts to look closely at the warrant application and the scope of the seizure.
Stops Seizures1995132 L. Ed. 2d 564
Vernonia School District 47J
Vernonia School District 47J v. Acton is important for police officers because it shows that not every Fourth Amendment search requires individualized suspicion, but it also shows that suspicionless searches are allowed only in limited settings. The Court’s reasoning depended heavily on the school environment, the special role of school officials, the voluntary nature of athletic participation, the reduced privacy expectations of student athletes, and the fact that the program was not designed as a criminal evidence-gathering tool.
Stops Seizures2002153 L. Ed. 2d 242
United States
United States v. Drayton is an important case for consent encounters, especially transportation interdiction work. Officers may approach people in public settings, including passengers on a bus, ask questions, request identification, and ask for consent to search, as long as the encounter remains voluntary under the totality of the circumstances.
Stops Seizures1997137 L. Ed. 2d 615
Richards
Richards v. Wisconsin is an important reminder that no-knock entry decisions must be based on facts, not labels. A search warrant involving drugs does not automatically justify skipping knock-and-announce.
Stops Seizures198583 L. Ed. 2d 604
United States
United States v. Hensley is important for patrol officers because it confirms that officers may act on wanted flyers, BOLOs, and similar interagency notices. An officer in the field does not have to stop and independently re-investigate the entire case before making a brief stop.
Stops Seizures198794 L. Ed. 2d 347
Arizona
Arizona v. Hicks is an important reminder that being lawfully present at a scene does not give officers unlimited authority to examine everything in the area. If officers enter a home because of an emergency, a protective sweep, a warrant, or another lawful reason, they may see things in plain view.
Stops Seizures1989104 L. Ed. 2d 1
United States
For officers, United States v. Sokolow reinforces that reasonable suspicion is a common-sense, total-picture standard. Officers should document the specific facts they knew before the stop and explain how those facts connected to suspected criminal activity.
Stops Seizures1990108 L. Ed. 2d 276
Maryland
Maryland v. Buie gives officers a safety tool during in-home arrests, but it also places clear limits on that tool. When making an arrest inside a residence, officers may check immediately adjoining areas where another person could quickly launch an attack.
Stops Seizures1998142 L. Ed. 2d 492
Knowles
Knowles v. Iowa is an important limitation on traffic-stop searches. If an officer stops a driver for a traffic offense and decides to issue a citation rather than make a custodial arrest, the officer does not get automatic authority to search the vehicle as a search incident to arrest.
Stops Seizures2021593 U.S. 345
United States
For tribal police officers, United States v. Cooley confirms that they may take reasonable enforcement action when they encounter a non-Indian on a public right-of-way within the reservation and have grounds to suspect a state or federal crime. The officer may investigate, address immediate safety concerns, and temporarily detain the person while contacting state or federal officers.
Stops Seizures1990110 L. Ed. 2d 301
Alabama
Alabama v. White gives officers a usable but limited rule for anonymous tips. If an anonymous caller reports criminal activity, officers should not assume the tip alone is enough for a stop.
Stops Seizures2005160 L. Ed. 2d 842
Illinois
Illinois v. Caballes is important for officers because it permits a drug-detection dog sniff during a valid traffic stop without requiring separate reasonable suspicion of drug activity. If the driver is lawfully stopped for a traffic violation, and a K-9 team is present or arrives while the stop is still being handled, the exterior sniff itself does not automatically create a Fourth Amendment problem.
Stops Seizures2006165 L. Ed. 2d 56
Hudson
Hudson v. Michigan does not mean officers can ignore the knock-and-announce rule. The rule remains part of Fourth Amendment law, unless a recognized exception applies, such as reasonable suspicion that announcing would create danger, allow evidence to be destroyed, or be futile.
Stops Seizures1998140 L. Ed. 2d 191
United States
United States v. Ramirez is important for warrant service and forced-entry planning. The case confirms that the key Fourth Amendment question is reasonableness under the circumstances, not whether the entry caused some property damage.
Stops Seizures2001148 L. Ed. 2d 838
Illinois
Illinois v. McArthur supports a careful, warrant-focused approach when officers have probable cause but do not yet have a search warrant. If officers reasonably believe evidence is inside a residence and that a person will destroy it if allowed inside alone, they may be able to hold the scene long enough to get a warrant without conducting a warrantless search.
Stops Seizures2011179 L. Ed. 2d 1149
Ashcroft
Ashcroft v. al-Kidd is not a general permission slip to use material witness warrants as a substitute for criminal probable cause. Officers should not read the case as saying that a material witness warrant can be obtained whenever investigators want to detain a person but lack evidence to arrest for a crime.
Stops Seizures198375 L. Ed. 2d 903
Kolender
Kolender v. Lawson is mainly a vagueness case, but it has important street-level consequences. Officers need to understand the difference between asking for identification and enforcing a criminal statute that requires identification.
Stops Seizures2000529 U.S. 266
Florida
Florida v. J. L.: florida v. <dot> <dot> is a key case for patrol officers responding to anonymous weapons calls. If the only information is an anonymous tip that a person at a location, wearing certain clothing, has a gun, officers should understand that matching the description alone may not be enough for a lawful Terry frisk.
Stops Seizures1996134 L. Ed. 2d 911
Ornelas
Ornelas v. United States is important for police work because it shows that reasonable suspicion and probable cause must be built on clearly described facts, not just conclusions. An officer’s experience matters, but the report and testimony must explain what the officer observed and why those observations mattered.
Stops Seizures2007168 L. Ed. 2d 132
Brendlin
Brendlin v. California: for officers, the main lesson is straightforward: when you stop a car, you are stopping the passengers too. A passenger may later challenge the legality of the stop and seek suppression of evidence that flows from it.
Stops Seizures2003157 L. Ed. 2d 343
United States
United States v. Banks is important for warrant service because it explains that knock-and-announce reasonableness is judged by real-world circumstances, not by a fixed stopwatch rule. Officers should still knock and announce when the Fourth Amendment requires it, but the amount of time they must wait before forced entry depends on what they are searching for, the risks present, and what happens at the door.
Stops Seizures2005161 L. Ed. 2d 299
Muehler
For officers, Muehler v. Mena confirms that a search warrant carries with it limited authority to control the scene by detaining occupants while the warrant is executed. If officers are lawfully inside executing the warrant, they generally do not have to let occupants move freely through the residence or leave the scene while the search is underway.
Stops Seizures2013185 L. Ed. 2d 19
Bailey
For officers serving search warrants, Bailey v. United States means that Summers detention authority has a geographic limit. If a person is on the premises or in the immediate area when the warrant is executed, officers may generally detain that person while the search is conducted.
Stops Seizures2006165 L. Ed. 2d 250
Samson
Samson v. California gives officers important authority when dealing with parolees, but it is not a blanket rule for every person or every supervision status. The decision applies to parolees who are subject to a valid search condition that allows searches without a warrant and without cause.
Stops Seizures2004159 L. Ed. 2d 292
Hiibel
Hiibel v. Sixth Judicial Dist. Court of Nev., Humboldt Cty.: for officers, Hiibel is important but limited. It does not create a general federal power to demand identification from anyone at any time.
Stops Seizures2000145 L. Ed. 2d 570
Illinois
For officers, Illinois v. Wardlow supports a stop when there is more than mere presence in a high-crime area. The key facts were Wardlow’s location in an area known for narcotics trafficking and his unprovoked flight as soon as he saw police.
Stops Seizures2002151 L. Ed. 2d 740
United States
United States v. Arvizu is an important reasonable-suspicion case for officers conducting investigative stops. The practical lesson is that courts should look at the whole picture, not isolate each factor.
Stops Seizures2009174 L. Ed. 2d 354
Safford Unified School District 1
For police officers, Safford Unified School District 1 v. Redding is a reminder that the Fourth Amendment focuses heavily on the degree of intrusion. A search that may begin lawfully can become unconstitutional if it becomes too invasive without specific facts supporting that level of intrusion.
Stops Seizures2009172 L. Ed. 2d 694
Arizona
Arizona v. Johnson is important because it separates two issues that officers must keep straight during traffic stops: the legality of the stop and the legality of the frisk. If the vehicle stop is lawful, the occupants are lawfully detained while the stop is being handled.
Stops Seizures2012183 L. Ed. 2d 351
Arizona
For officers, Arizona v. United States is an important reminder that immigration status can be relevant during a lawful police encounter, but it does not automatically create state arrest authority. If an officer has lawfully stopped or arrested someone for a valid reason, the officer may be able to contact federal immigration authorities or make a reasonable status inquiry consistent with agency policy and state law.
Stops Seizures2016579 U.S. 232
Utah
Utah v. Strieff does not give officers permission to stop people without reasonable suspicion. The initial stop in the case was treated as unlawful, and the Court’s ruling depended heavily on the later discovery of a valid, pre-existing warrant and the absence of purposeful or flagrant misconduct.
Stops Seizures2012182 L. Ed. 2d 566
Florence
Florence v. Board of Chosen Freeholders of County of Burlington: for patrol officers, the main lesson is that the constitutional analysis changes once a person is lawfully arrested and brought into a jail for admission to the general population. The Supreme Court gave substantial deference to correctional officials’ need to keep contraband, weapons, and other risks out of the jail environment.
Stops Seizures2014188 L. Ed. 2d 680
Prado Navarette
For officers, Prado Navarette v. California supports stopping a vehicle based on a 911 report when the caller gives specific information, appears to be reporting firsthand and recent events, and describes dangerous driving that may suggest impairment or an immediate threat to public safety. Officers do not always need to personally observe a new traffic violation before stopping the vehicle, if the tip itself provides reasonable suspicion.
Stops Seizures2015575 U.S. 348
Rodriguez
For officers, Rodriguez v. United States means the clock matters, but the reason for the time matters even more. During a traffic stop, officers may take the time reasonably needed to address the traffic violation, run normal records checks, verify documents, and take legitimate safety precautions.
Stops Seizures2020589 U.S. 376
Kansas
For patrol officers, Kansas v. Glover supports a traffic stop when a records check shows that the vehicle’s registered owner has a revoked license and there is no information suggesting the owner is not behind the wheel. The officer does not have to first observe a separate traffic violation, and the officer does not have to positively identify the driver before the stop, as long as the stop is based on reasonable suspicion under the circumstances.
Stops Seizures1990110 L. Ed. 2d 412
Michigan Department of State Police
For police officers, Michigan Department of State Police v. Sitz means that DUI checkpoints are not automatically unconstitutional just because officers lack individualized suspicion for each driver stopped. A checkpoint may be lawful if it is structured, limited, and aimed at roadway safety rather than general crime control.
Police Pursuits2007550 U.S. 372
Scott
Scott v. Harris is the Supreme Court's major police-pursuit force case. It explains when force used to end a dangerous high-speed chase can be reasonable under the Fourth Amendment.
Police Pursuits200383 P.3d 75
Tidwell
Tidwell v. City and County of Denver is a Colorado police-pursuit case explaining that a chase can legally count as a pursuit even without lights and siren, and that emergency-signal requirements can affect governmental immunity.
Stops and Seizures1996517 U.S. 806
Whren
In Whren v. United States, the Supreme Court unanimously held that a traffic stop supported by probable cause does not violate the Fourth Amendment just because officers may have had an additional investigative motive. The decision affirmed an objective Fourth Amendment rule for traffic stops.
Evidence Procedure1984468 U.S. 897
United States
United States v. Leon, 468 U.S. 897 (1984), held that the exclusionary rule generally does not bar evidence seized by officers who reasonably rely in good faith on a search warrant later found invalid. The decision created a major Fourth Amendment doctrine while preserving suppression for serious police misconduct or plainly unreliable warrants.
Technology Privacy Surveillance2012565 U.S. 400
United States
United States v. Jones held that the government's installation and use of a GPS tracker on a vehicle was a Fourth Amendment search. The decision emphasized that Katz privacy analysis did not replace the older rule protecting people against physical government trespass on persons, houses, papers, and effects to obtain information.
Stops and Seizures1968392 U.S. 1
Terry
Terry v. Ohio, 392 U.S. 1 (1968), upheld a limited stop and frisk based on reasonable suspicion and safety concerns. The decision recognized that stops and frisks are Fourth Amendment events, but allowed a narrow weapons pat-down without probable cause when specific facts make the intrusion reasonable.
Qualified Immunity Civil Rights2001533 U.S. 194
Saucier
Saucier v. Katz held that qualified immunity in excessive force cases is not identical to the Fourth Amendment reasonableness inquiry. Courts must separately consider whether the alleged facts show a constitutional violation and whether that right was clearly established in the specific circumstances. The Court granted qualified immunity to the military police officer.
Technology Privacy Surveillance2014573 U.S. 373
Riley
Riley v. California, 573 U.S. 373 (2014), held that the Fourth Amendment generally requires police to get a warrant before searching digital information on a cell phone seized incident to arrest. The Court balanced law enforcement needs against the uniquely broad privacy interests in modern phones and left room for exigent circumstances in urgent cases.
Use of Force2014572 U.S. 765
Plumhoff
Plumhoff v. Rickard held that officers did not violate the Fourth Amendment when they used deadly force to stop a person fleeing police in a high-speed chase that endangered the public. The Court also held the officers were protected by qualified immunity in any event.
Qualified Immunity Civil Rights2009555 U.S. 223
Pearson
Pearson v. Callahan changed qualified immunity procedure. The Court held that judges are no longer required to decide the constitutional violation question before asking whether the law was clearly established. The officers won qualified immunity because existing law had not clearly prohibited the warrantless entry under the consent-once-removed theory.
Special Contexts1985469 U.S. 325
New Jersey
In New Jersey v. T.L.O., the Supreme Court held that public school officials are bound by the Fourth Amendment, but student searches in school are governed by a special reasonableness standard. Schools do not usually need a warrant or probable cause. They need reasonable grounds at the start and a search that stays reasonably related in scope.
Qualified Immunity Civil Rights1978436 U.S. 658
Monell
In Monell, the Supreme Court overruled part of Monroe v. Pape and held that local governments are 'persons' under § 1983. Municipalities may be liable when official policy or custom causes a constitutional violation, but not simply because they employ the person who committed the violation.
Miranda Interrogation1966384 U.S. 436
Miranda
In Miranda v. Arizona, the Supreme Court held that statements from custodial interrogation generally cannot be used unless law enforcement first provides warnings protecting the privilege against self-incrimination and the right to counsel, and any waiver is voluntary, knowing, and intelligent.
Searches Warrants1961367 U.S. 643
Mapp
In Mapp v. Ohio, 367 U.S. 643 (1961), the Supreme Court reversed Dollree Mapp's conviction and held that evidence obtained through unconstitutional searches and seizures cannot be used in state criminal trials. The decision made the exclusionary rule binding on state and local law enforcement through the Fourteenth Amendment.
Searches Warrants1967389 U.S. 347
Katz
In Katz v. United States, 389 U.S. 347 (1967), the Supreme Court reversed a conviction based on warrantless recordings from a public phone booth. The Court held that the Fourth Amendment protects people, not places, and that electronic surveillance of a private conversation can be a search even without physical trespass.
Evidence Procedure2009555 U.S. 135
Herring
In Herring v. United States, 555 U.S. 135 (2009), the Supreme Court held that evidence found after an arrest based on an outdated warrant record did not have to be suppressed. The exclusionary rule turns on whether suppression would deter sufficiently culpable police conduct, not on every negligent recordkeeping mistake.
Stops and Seizures2014574 U.S. 54
Heien
In Heien v. North Carolina, the Supreme Court held that an officer's objectively reasonable mistake about the law can still create reasonable suspicion for a traffic stop under the Fourth Amendment. The stop began with one nonworking brake light, even though state law was later read to require only one working stop lamp. The Court affirmed because the statutory language made the officer's interpretation reasonable.
Qualified Immunity Civil Rights1982457 U.S. 800
Harlow
Harlow v. Fitzgerald, 457 U.S. 800 (1982), created the modern objective qualified immunity test: federal officials performing discretionary duties are protected from damages unless they violate clearly established rights a reasonable official would have known.
Special Contexts1987483 U.S. 868
Griffin
In Griffin v. Wisconsin, the Supreme Court upheld a warrantless search of a probationer's home under a Wisconsin regulation requiring reasonable grounds and supervisor approval. The Court treated probation supervision as a special need beyond ordinary law enforcement, allowing a limited departure from the usual warrant and probable-cause rules.
Use of Force1989490 U.S. 386
Graham
Graham v. Connor established that police excessive-force claims during arrests, stops, or seizures are governed by Fourth Amendment objective reasonableness. The rule focuses on the facts confronting officers at the scene, including severity of the suspected offense, immediate safety threats, and resistance or flight, while avoiding hindsight and subjective-intent tests.
Miranda Interrogation1981451 U.S. 477
Edwards
Edwards v. Arizona held that once a person in custody invokes the Miranda right to counsel, police cannot initiate further custodial interrogation unless counsel is provided or the person initiates further communication and validly waives the right.
Use of Force2017581 U.S. 420
County of Los Angeles
In County of Los Angeles v. Mendez, the Supreme Court rejected the Ninth Circuit's provocation rule. The Court held that a prior Fourth Amendment violation does not automatically convert a later reasonable use of force into unconstitutional excessive force, though the prior violation may still support damages under proximate-cause principles.
First Amendment Public Order1987482 U.S. 451
City of Houston
In City of Houston v. Hill, 482 U.S. 451 (1987), the Supreme Court struck down a Houston ordinance that criminalized interrupting police officers. The Court held that the ordinance swept too broadly into protected speech and gave police too much discretion to arrest people for verbal criticism or challenge.
Qualified Immunity Civil Rights1989489 U.S. 378
City of Canton
City of Canton v. Harris held that a municipality can be liable under § 1983 for failure to train police employees, but only when the failure reflects deliberate indifference to constitutional rights and causes the injury. The case is a foundation of modern Monell municipal-liability doctrine.
Searches Warrants1925267 U.S. 132
Carroll
Carroll v. United States, 267 U.S. 132 (1925), upheld a warrantless search of an automobile during Prohibition because officers had probable cause to believe it carried illegal liquor. The decision established the automobile exception: mobility can make a warrant impractical, but probable cause remains required.
Technology Privacy Surveillance2018585 U.S. 296
Carpenter
In Carpenter v. United States, the Supreme Court held that law enforcement's acquisition of extensive historical cell-site location information is a Fourth Amendment search. A lower Stored Communications Act order was not enough; a probable-cause warrant is generally required for this kind of detailed location tracking.
Evidence Procedure1963373 U.S. 83
Brady
Brady v. Maryland requires prosecutors to disclose material evidence favorable to the accused when it bears on guilt or punishment. The rule protects the fairness of criminal trials and applies regardless of whether the prosecution acted in good or bad faith.
Miranda Interrogation2010560 U.S. 370
Berghuis
In Berghuis v. Thompkins, the Supreme Court held that a suspect who has received and understood Miranda warnings must clearly invoke the right to remain silent. Remaining mostly silent during an interrogation does not, by itself, require police to stop questioning, and an uncoerced answer can amount to an implied waiver.
Searches Warrants2009556 U.S. 332
Arizona
Arizona v. Gant held that police cannot automatically search a vehicle just because they arrested a recent occupant. A search incident to arrest is allowed only if the arrestee could access the vehicle at the time of the search, or if officers reasonably believe the vehicle contains evidence of the offense of arrest.
Use of Force1985471 U.S. 1
Garner
Tennessee v. Garner sets the constitutional standard for deadly force against fleeing suspects.