However, before an officer can arrest a driver for drunk driving, the officer must have probable cause that the driver was driving while intoxicated. Probable cause is higher standard than reasonable suspicion. Thus, swerving a little bit doesn’t give an officer the right to arrest a driver for drunk driving. Indeed, the officer must pull over the driver and assess the situation and, after field sobriety tests or observation, know with reasonable certainty that the driver is intoxicated before he may arrest him or her for drunk driving.
There is also a “presence” element is drunk driving laws – thus, a driver may argue that, “I was pulled over on the side of the road, and I wasn’t driving when the officer saw me. So, how could he say that I was driving drunk – he never saw me drive.”
The majority of the states do away with the “presence” element in the drunk driving context – because a drunk driver poses a danger to other drivers and because a police officer cannot simply issue a citation to a drunk driver and let him go on his or her way. Thus, most states say that the officer doesn’t actually have to observe the driver driving intoxicated – so long as all the surrounding circumstances indicate the vehicle could not otherwise be located where it was unless driven there by that person.