Most people, when they see a police car on the side of the road or driving near them in traffic, tend to get a bit nervous. It’s a natural reaction, as if we all think that the officer may decide to pull us over. We act like they have the right to do that to any car, at any time.

That’s not actually how it works, though. The police need a reason for every traffic stop. They must have probable cause.

This often gets brought up in connection to DUI charges or drug charges. An officer who wants to search cars for drugs cannot just randomly start pulling vehicles over and carrying out the searches. Even if they found something, they may not be able to use it in court if it turned out to be illegally obtained evidence.

The same is true for drunk drivers. Police may believe they have drunk drivers leaving a certain event or driving at a certain time of night, but they can’t start pulling over cars to give out breath tests and force people through field sobriety tests. They need a reason for the stop, like seeing the driver roll through a stop sign or watching them weave out of their lane. Only after a valid stop can they start considering the possibility of a DUI.

That said, remember that police officers can stop you for all sorts of things, such as a cracked taillight or driving just slightly over the speed limit. If they do stop you and you end up facing DUI charges, you need to know what steps to take.