Police officers are trained to look for certain signs to decide whether to pull a driver over on suspicion of drunk driving. The National Highway Traffic Safety Administration (NHTSA) teaches officers that there are four categories of driving behaviors which they should look for. These four categories are: 1) problems in maintaining proper lane position; 2) speed and braking problems; 3) vigilance problems; and 4) judgment problems. These categories are broken down further into 24 of what NHTSA calls cues. If a driver exhibits one or more of these cues while driving a car in the presence of a patrol car, he/she is likely to be pulled over on suspicion of DWI.
All 24 of these cues are published by NHTSA. Some of the more commonly observed ones are weaving, straddling a lane line, wide turns, driving without headlights at night, driving 10 mph or more under the speed limit, tailgating, turning improperly, and making an improper/unsafe lane change. Importantly, speeding is not a cue. While speeding is likely to get a driver pulled over, it is not considered to be a drunk driving cue. One other important cue is "appearing to be impaired." For example, gripping the wheel too tight can get a driver pulled over. In addition to the driving cues, there are 10 of what NHTSA refers to as post stop clues. After they pull a driver over, the following clues are what officers look for to decide whether to conduct a DWI investigation (it is not clear why these are "clues" and the driving cues are "cues"):
- Difficulty with motor vehicle controls
- Fumbling with driver license or registration
- Difficulty exiting the vehicle
- Repeating questions or comments
- Swaying, unsteady, or balance problems
- Leaning on the vehicle or other object
- Slurred speech
- Slow to respond to officer/officer must repeat
- Provides incorrect information, changes answers
- Odor of alcoholic beverage from the driver
If an officer, after pulling a driver over, observes some of the above behaviors, he/she will likely request the driver to get out of his/her car and administer Field Sobriety Tests. It is unlikely that a very drunk person will be able to avoid exhibiting some of the above clues, despite knowing what officers look for. However, for someone who has only had a few drinks, it is worth knowing how to avoid "looking drunk."