Patrick Morley
Vice President
McCarthy Byrnes
May 11, 2026
Foundational Fourth Amendment & Arrest Cases (Part 3)
As we continue our series on the 40 essential use‑of‑force cases every law enforcement professional should know, we now turn to the foundational Fourth Amendment and arrest‑authority decisions that shape daily policing. These cases define when officers may stop, detain, frisk, arrest, and use force during those encounters.
While the focus remains on U.S. Supreme Court precedent, remember state law, state constitutions, and agency policy may be more restrictive. Supreme Court decisions establish the constitutional minimum-not the operational standard.
Understanding these rulings helps officers recognize the legal boundaries of investigative stops, flight‑based detentions, custodial arrests, and mistakes of law. These cases directly influence when force is justified and how courts evaluate officer decision‑making in the field.
11. Terry v. Ohio, 392 U.S. 1 (1968)
Fact Pattern
A veteran officer observed two men repeatedly pacing in front of a store, appearing to case it for a robbery. He stopped them based on reasonable suspicion and conducted a pat‑down, discovering a firearm.
Rule
Officers may stop individuals based on reasonable suspicion of criminal activity and may frisk them if they reasonably believe the person is armed and dangerous. The force used during a Terry stop must be limited, brief, and proportional to the threat.
Why It Matters
Terry is a landmark case and the foundation of modern investigative policing. Most force used during non‑arrest encounters: hands‑on control, pat‑downs, brief detentions-flows from Terry authority. Officers must be able to clearly articulate the specific facts that created reasonable suspicion and justified any force used. It should be noted that the Court found that the officer acted on more than a “hunch” and that “a reasonably prudent man would have been warranted in believing the defendant was armed and thus presented a threat to the officer’s safety while he was investigating his suspicious behavior.
12. Illinois v. Wardlow, 528 U.S. 119 (2000)
Fact Pattern
Officers patrolling a high‑crime area saw Wardlow holding an opaque bag. When he made eye contact with police, he immediately fled. Officers pursued, stopped him, and discovered a firearm.
Rule
Unprovoked flight in a high‑crime area contributes to reasonable suspicion and justifies a stop. Officers may pursue and detain individuals under these circumstances.
Why It Matters
Wardlow is central to understanding suspect‑initiated escalation. When a subject flees, officers may use reasonable force to stop the flight. The case reinforces that context-such as crime patterns and officer experience-matters when evaluating reasonable suspicion. (It should be noted that in this case, police were on patrol in a high crime area, the defendant was holding a bag, but upon looking in the direction of the police, began to flee. Additionally, under California v. Hodari D, 499 U.S. 621 (1991) that a fleeing suspect is not “seized” under the terms of the 4th Amendment unless the pursuing officers apply physical force to the suspect or the suspect submits to officers’ demands to halt)
13. Atwater v. City of Lago Vista, 532 U.S. 318 (2001)
Fact Pattern
A woman was arrested for a seatbelt violation punishable only by a fine. She challenged the custodial arrest as unreasonable under the Fourth Amendment.
Rule
Custodial arrests for fine‑only misdemeanors are constitutional. Even minor offenses may justify a full custodial arrest when supported by probable cause.
Why It Matters
Atwater expands officer discretion during low‑level encounters. If an arrest is lawful, the force used to effect that arrest is judged under Graham v. Connor, regardless of the offense’s severity. Agencies may impose stricter policies, but constitutionally, the authority is broad.
14. Devenpeck v. Alford, 543 U.S. 146 (2004)
Fact Pattern
An officer arrested a driver for an offense that was not actually a crime, but probable cause existed for a different offense. The arrestee argued the arrest was invalid because the officer cited the wrong reason. In this case, the arrested offender was stopped on the roadside to assist a stranded motorist, and his “wig‑wag” headlights made the police suspect he was impersonating a police officer . The offender abruptly drove off, and was stopped by police, who observed handcuffs and a police scanner, further heightening suspicion When a police supervisor arrived, he discovered the arrestee covertly recording the encounter and arrested him under the Washington Privacy Act, even though recording an officer during a traffic stop was legal and the charge was later dropped . The arrestee then filed a Section 1983 suit, and the Supreme Court took the case to determine whether an arrest can be valid when the officer cites the wrong offense.
Rule
An arrest is constitutional if probable cause exists for any offense, even if the officer states a different or incorrect reason. Subjective intent does not matter.
Why It Matters
Devenpeck protects officers when the legal label is mistaken but the facts support probable cause (in this case, charges related to impersonating a police officer). This directly affects force justification: if the arrest is valid under any offense supported by probable cause, the force used to effect that arrest is evaluated under Graham.
15. Heien v. North Carolina, 574 U.S. 54 (2014)
Fact Pattern
An officer stopped a vehicle for having only one working brake light, believing state law required two. During the course of the stop, police became suspicious of the actions of the occupants. Police obtained consent to search, and found cocaine in the vehicle. The law was ambiguous, and the stop was challenged as unconstitutional.
Rule
A traffic stop based on a reasonable mistake of law does not violate the Fourth Amendment. If the officer’s interpretation of the law is objectively reasonable, the stop is valid.
Why It Matters
Heien expands lawful stop authority by recognizing that officers may make reasonable legal mistakes. Any force used after such a stop is still judged under Graham, but the stop itself remains constitutional if the mistake was reasonable. (It should be noted that police personnel should be cautious about certain holdings in this opinion. Police are presumed to know the law,immediately upon passage of a law, or when a new case is decided. In this case, the law was vague, so police were found to be acting in good faith.)
Parting Thoughts (Part 3)
These five cases form the backbone of modern stop, detention, and arrest authority. They clarify:
- When officers may detain based on reasonable suspicion
- How flight affects the legality of force
- When custodial arrests are permitted
- How probable cause supports arrests even when the stated reason is incorrect
- How reasonable mistakes of law impact stop authority
For officers and supervisors, the operational takeaway is clear: Your authority to detain, frisk, and arrest directly shapes the legality of any force used during those encounters. Understanding these cases strengthens decision‑making, articulation, and courtroom defensibility.
More cases-16 through 20-will follow soon as we continue building a practical, working command of the law governing use of force in the field. This next article will examine corrections, jail, and prison use of force cases. These are an area of great potential civil liability for Departments of Corrections and Sheriff’s Offices, and is also relevant for police departments who detain arrestees before they appear before a judge.
