486 U. S. 567
June 13, 1988
One day in Detroit, a drug dealer saw a police car, and broke into a sprint. The police car followed him, and during the chase, the crook dropped drug packets. After his arrest, he claimed that the chase was an unlawful seizure of his person, because the police had no basis for suspecting criminal activity apart from his sprinting. The police responded that the bare act of following someone in a police car is not a Fourth Amendment seizure.
The Supreme Court unanimously agreed with the police. Blackmun stated that the test for seizure is whether a reasonable person would feel they were free to leave. In the case at hand, the police issued no order to halt, did not turn on the car siren, and did not use the car to block the runner. Thus, Blackmun concluded that a seizure had not quite been committed, for a reasonable person could conclude that they were merely being monitored rather than completely stopped.
In a concurrence joined by Scalia, Kennedy noted that the Court had not decided if clear communication of an impending, but not yet effected seizure violated the Fourth Amendment. Shockingly, Brennan and Marshall did not dissent from the Court’s holding. I guess there has to be some limit to their pro-criminal obsession, but it’s always a shock to catch a glimpse of that limit.