The length of time an officer may legally detain someone is not clearly defined, and varies based on the circumstances surrounding the encounter. Generally, an officer may only detain you for as long as it takes to conduct an investigation for the violation you are suspected of committing. Thus, a person stopped for speeding should expect a shorter encounter than a person suspected of a DWI, where sobriety tests may need to be conducted. Generally, a routine traffic stop should take between 10 and 20 minutes from when you pull over to your final interaction with the officer. Stops exceeding this time frame begin to edge into the murky area of unnecessary detention, and the officer should have a clear reason to continue the investigation.
If you feel that you are being detained unlawfully by an officer, the first thing you should do is ask if you are being detained or if you are free to leave. Until you do so, your detention is considered voluntary, even if you have expressed your choice to remain silent or declined a search. If you don’t verbally ask to be let go you are, according to the law, volunteering to be detained.
When you ask this question, the officer must either let you go, or have a valid reason to continue to detain you. If you are not released, you should immediately sate your desire to speak with a lawyer. This makes it much more difficult for an officer to extend your detention. If you are released, however, you should leave immediately. Otherwise you are considered to be volunteering to remain under police custody and the investigation may continue.
Asking to be allowed to go may not always prevent an officer from continuing to detain you and move forward with an investigation, regardless of whether they have legal grounds to do so. However, it is more likely that a judge will find such detention unlawful and throw out any evidence found against you during the extended investigation if you use your rights and ask to be released.