What is a common sign of a driver who has been drinking?

Swerving or inconsistent lane positioning is a common sign of a driver who has been drinking because alcohol impairs coordination, balance, and judgment. These impairments affect a driver's ability to maintain a steady course within their lane and respond appropriately to the vehicle's handling. As a result, you may notice erratic movements such as weaving in and out of lanes or failing to keep a straight line while driving.

In contrast, excessive speed might suggest aggressive driving behavior, which is not exclusively linked to alcohol consumption and can also occur in sober drivers seeking to get to their destination quickly. Frequent stopping may be indicative of cautious driving or uncertainty, but it doesn't directly signal impairment from alcohol. Using turn signals excessively is not typically associated with drunk driving behaviors; instead, it could reflect anxiety or a lack of awareness, which is not as strongly correlated with impairment as swerving or erratic lane changes.