The court ruled that, while it is legal for authorities to target and approach a person based on their behavior, absent more, they cannot detain or search such individual without a warrant.

In January 1978, two undercover officers approached the plaintiff, Mr. Royer, at the Miami International Airport because he fit a drug courier profile: He was a casually dressed, nervous young man carrying heavy luggage.

He became visibly nervous when the officers noted that the ticket and driver's license bore different names, and then they told him they suspected him of transporting narcotics.

The officers should not have asked the suspect to accompany them from the point of the initial consensual encounter to the small room until they returned his ticket and license.

Since the officers only had reasonable suspicion, not probable cause to believe he was transporting narcotics until they opened the suitcase and found the marijuana (which they admitted in court), they had no legal right to place Mr. Royer in custody.