What type of seizure occurs when a person is told they can leave but are not free to do so?

The scenario described in the question pertains to a type of seizure known as a detention. This occurs when a person is not free to leave despite being told they can do so. In legal terms, a detention is a temporary and brief seizure of an individual by law enforcement for investigative purposes, based on reasonable suspicion of involvement in criminal activity.

A key aspect of a detention is that while the individual may be informed they can leave, the circumstances or the way they are approached by law enforcement create a situation where they feel they cannot, or are not truly free to go. This ambiguous situation distinguishes detention from other types of encounters, such as an arrest, which involves the actual deprivation of liberty and is typically based on probable cause.

In contrast to detention, an arrest involves a formal charge and a higher level of authority, and a voluntary encounter indicates that the individual is free to leave at any time and not under any compulsion to stay or answer questions. A search, on the other hand, pertains to the examination of a person's property or person, rather than their personal liberty.