Being pulled over by the police is an experience that can make you very nervous. One of the primary questions most people have when they’re in this position is what led the officer to choose their vehicle for a traffic stop. This is sometimes an easy question, such as when a person runs a red light or is speeding.

Sometimes, the reason isn’t immediately clear. In order to conduct a traffic stop, the officer needs to have reasonable suspicion. This is a much easier standard for them to meet than when they need probable cause.

Small behavioral changes that are associated with impaired driving can meet the standard. This means that if the officer observes you swerving or braking unnecessarily, they can pull you over. The same is true if you’re straddling the centerline, almost hitting objects on the side of the road, driving too fast or too slowly, failing to signal or driving without your headlights on when it’s dark.

Once the cop pulls you over, they will try to find out what’s going on. This will usually involve speaking to you. They may also ask you to submit to a chemical test or a field sobriety test to try to determine whether you’re impaired or not.

In order to arrest you, they need probable cause. This can come in the form of a blood alcohol concentration (BAC) test with a result above the legal limit. The results of a standardized field sobriety test can also meet the requirement.

If you’re pulled over and then arrested on the suspicion of drunk driving, you should review your options for a defense. These vary based on the circumstances of the case, so review the options carefully. An attorney can help you determine which defense you should use in your case.