In which case was it determined that a significant deprivation of freedom of movement constitutes a seizure?

The determination that a significant deprivation of freedom of movement constitutes a seizure comes from the case Terry v. Ohio. In this landmark decision, the U.S. Supreme Court established that a seizure occurs when a law enforcement officer stops a person and restricts their movement in a significant way, even if the individual is not formally arrested. This case involved the "stop and frisk" principle, where the Court ruled that an officer could briefly detain a person based on reasonable suspicion that the individual is involved in criminal activity. The Court's opinion highlighted that any action by law enforcement that meaningfully restricts a person's freedom of movement can be considered a seizure under the Fourth Amendment, thereby requiring a legal justification for such actions. This principle is crucial in assessing law enforcement conduct and ensuring the protection of individual rights against unreasonable searches and seizures.