According to research by the National Highway Traffic Administration, police officers look for drunk drivers based on the following:
- making a wide radius turn;
- straddling the center lane marker;
- "appearing" to be drunk;
- almost striking an object or vehicle;
- weaving;
- a designated highway where many drivers are suspected to be drunk;
- swerving;
- speed at more than 10 miles per hour below the speed limit;
- stopping without cause in a traffic lane;
- following too closely;
- drifting;
- tires on center lane marker;
- braking erratically;
- driving into opposing lanes or across traffic;
- signaling inconsistent driving action;
- slow response to traffic signals;
- stopping inappropriately;
- turning abruptly or illegally;
- accelerating or decelerating rapidly;
- headlights off.
These elements are very important because, according to the Unites States Constitution, a person cannot be stopped or searched without a reason. The police must have a reason to stop the person and if they are to investigate for DUI must show that they had a reason to believe the person may be intoxicated.
