Flight and the Fourth Amendment
Sometimes, people run when they see you coming. May you chase them? If you do, does that amount to a "show of authority" constituting a detention, requiring reasonable suspicion?

Sometimes, people run when they see you coming. May you chase them? If you do, does that amount to a "show of authority" constituting a detention, requiring reasonable suspicion? If they throw down contraband or a weapon during the chase and you recover it, is that the "fruit" of an illegal detention? Can they be arrested for illegal possession, or for resisting a lawful command to stop?
As usual, the answer is, "It all depends." It depends on the circumstances at the start of the flight, actions you take to accomplish a detention, and how the chase ends. Three U.S. Supreme Court cases hold the answers.
Michigan V. Chesternut
Detroit officers in a marked car saw a car pull to the curb near an intersection where Michael Chesternut was standing alone. When Chesternut saw the patrol car, he turned and began to run. The patrol car followed around the corner and drove alongside him, without red lights, sirens, commands, or attempts to block his path. Chesternut threw down pill packets; the officers retrieved them and recognized their contraband nature, and then stopped and arrested Chesternut.
Michigan courts ordered the pills suppressed as the "fruit" of an unlawful detention, holding that "any investigatory pursuit amounts to a seizure, and as soon as the officers began their pursuit," Chesternut was detained. Because officers had no suspicion of criminal activity before the pursuit, the state courts concluded Chesternut was unlawfully detained, and the pills were the "tainted fruit" of that illegality. The state appealed, and the U.S. Supreme Court unanimously reversed, saying the following:
"Defendant was not seized by the police before he discarded the packets containing the controlled substance. While the very presence of a police car driving parallel to a running pedestrian could be somewhat intimidating, this kind of police presence does not, standing alone, constitute a seizure. The police therefore were not required to have a particularized and objective basis for suspecting defendant of criminal activity."
California V. Hodari D.
Police officers wearing distinctive raid jackets and driving an unmarked car were patrolling a high-crime neighborhood in Oakland, Calif., when a group of young men standing near a parked car saw the undercover car approaching and scattered. One officer left the police car and went in foot pursuit of Hodari, who tossed a rock of crack cocaine as he ran up the street. The officer overtook Hodari, tackled him, and cuffed him.
Charged in juvenile court, Hodari moved to suppress the crack, and the California Court of Appeal granted the motion. That court said that Hodari was "seized when he saw the officer running towards him," and the discarded narcotic was a result of an unlawful detention, unsupported by reasonable suspicion. On the state's appeal, the U.S. Supreme Court reversed.
As it already had done in Chesternut, the court again rejected the notion that there is such a thing as an unlawful "attempted detention" or "threatened detention." Even if an officer yells, "Stop! Police!" a person who does not stop has not been seized. The court explained that a person is not "seized" until he submits in response to the show of authority, or has been physically restrained by police. That's the point in time at which reasonable suspicion would be required; contraband discarded before a seizure actually occurs cannot be the product of that seizure. The court said this:
"Street pursuits always place the public at some risk, and compliance with police orders to stop should therefore be encouraged. Assuming that the officer's pursuit in this case constituted a show of authority enjoining Hodari to halt, since Hodari did not comply with that injunction he was not seized until he was tackled. The cocaine abandoned while he was running was in this case not the fruit of a seizure, and his motion to exclude evidence of it should be denied."
Illinois V. Wardlow
Uniformed officers on patrol in an area of Chicago known for heavy narcotics trafficking saw William Wardlow standing near a building. He looked in their direction and then fled. Officers gave chase, cornered him, and detained him. A protective patdown revealed a loaded handgun illegally carried, and Wardlow was arrested.
The Illinois Appellate Court and Illinois Supreme Court ruled that Wardlow was unlawfully detained without reasonable suspicion, and ordered the gun suppressed. The U.S. Supreme Court reversed. Although agreeing that a person's mere presence in a high-crime area is not enough by itself to justify detention, the court said that when coupled with sudden flight, adequate justification exists.
In the court's words, "It was not merely defendant's presence in an area of heavy narcotics trafficking that aroused the officer's suspicion, but his unprovoked flight upon noticing the police. Evasive behavior is a pertinent factor in determining reasonable suspicion. Headlong flight is the consummate act of evasion. We conclude that the officer was justified in suspecting that Wardlow was involved in criminal activity, and, therefore, in investigating further."
In practice, officers intending to rely on Wardlow to validate detentions of suspects who flee and are pursued and caught should be prepared to explain why they consider an area a "high-crime" location. For example, departmental statistics on the number of drug or other arrests made at a location, or within a particular radius and within a specified period of time before the incident, might be sufficient. It would generally not be enough to simply make the unsupported claim that a certain place was a high-crime area.
If you go in foot pursuit of a suspect who runs on your approach in a high-crime area, you should yell, "Stop! Police!" as you chase him. This will constitute an attempt to make a lawful detention. A suspect who continues fleeing would then be in violation of any applicable statutes making it a crime to resist, delay, obstruct, or interfere with a police officer in the lawful performance of official duties, and provide a ground for arrest (and therefore a full search incident to arrest).
Summary
Driving alongside a fleeing suspect without lights, sirens, commands to stop, or efforts to block his path, is not a Fourth Amendment detention. No justification is necessary.
Running after a fleeing suspect and ordering him to stop is not a detention if he doesn't stop. No detention occurs until he submits, or you capture him.
Anything the suspect discards while fleeing is not the fruit of any detention, and therefore should not be suppressed. If you have PC to believe the discard is contraband or evidence of a crime, that can establish PC for arrest and search.
Even if you have no other suspicion of criminal conduct, when a person flees upon your approach in a high-crime area, you can lawfully detain him or her. You attempt such a lawful detention by loudly yelling, "Stop! Police!" The subject's continued flight from a lawful attempted detention would be PC to arrest for resisting, delaying, obstructing, or interfering.
Check Local Restrictions
Courts in a few states interpret state constitutional provisions as imposing greater restrictions on law enforcement officers than the federal constitution. Officers in those states should always check with local advisors for any variations.
Devallis Rutledge is a former police officer and veteran prosecutor who currently serves as special counsel to the Los Angeles County district attorney. He is the author of 12 books, including "Investigative Constitutional Law."
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