How do you know when a lawful arrest occurs if you are being investigated for DUI-DWI? Because of the application of the exclusionary rule to evidence obtained after an unlawful arrest and because of the importance of the arrest for purposes of Miranda warnings and the application of implied consent laws, it often becomes necessary to determine exactly when an arrest occurred.

An arrest is generally deemed to have occurred when a reasonable person would have understood that he or she was no longer free to leave. In determining when an arrest occurs, the issue is when the defendant reasonably believed that he or she was under arrest, not necessarily when the police officer subjectively believed an arrest had occurred. In some states, it should be noted, there is a statutory definition of when an arrest occurs.

The stopping of a vehicle by a police officer is not normally considered an arrest. Even the opening of a car door by a police officer does not usually constitute an arrest. It is only when a reasonable person would believe that he or she had no choice but to accompany the officer that an arrest occurs.