Unless you are going through a DUI checkpoint, officers must have a reason to pull you over and administer a field sobriety test. While most people may associate weaving or crossing over the lane lines as a sign of an impaired driver, there are also other behaviors police officers are looking for. Knowing what these signs are can help defendants better understand if the officer had enough evidence to warrant the traffic stop in the first place.
Before an officer pulls you over, he or she will be observing the car while it is moving. In many cases, the officer will be driving behind the vehicle to be able to better determine any erratic driving patterns. These may include risky driving behaviors, such as cutting people off or not ensuring an assured clear distance ahead, braking in unnecessary places or coming to a complete stop for no reason. Driving too slowly can also be a sign of an impaired driver who is concentrating or trying to avoid getting pulled over for speeding.
Once the officer pulls you over, he or she will then be watching for signs of impairment during interactions with you. Slurred speech, immediately beginning to smoke or chew gum to mask the smell of alcohol, open containers and bloodshot eyes are all potential indicators of an impaired driver.
If the officer believes there is enough evidence to suspect you of driving under the influence, you will likely be asked to step out of the car for a field sobriety test, which can include balance tests or a Breathalyzer. Failing any of these tests will result in a DUI arrest, and the officer will take you back to the police station for booking.
Source: Ohio State Bar Association, "Police Identify Drunk Drivers through Signs of Impairment," accessed April. 16, 2015