A: The following list of clues indicate what police look for when trying to establish whether the driver being observed is impaired. The higher the clue is on the list, the higher the probability of impairment. The list is based on research by the National Highway Traffic Administration:
- Turning with a wide radius
- Straddling center of lane marker
- "Appearing to be drunk"
- Almost striking object or vehicle
- Weaving
- Driving on other than designated highway
- Swerving
- Speed more than 10 mph below limit
- Stopping without reason in traffic lane
- Following too closely
- Drifting
- Tires on center or lane marker
- Braking erratically
- Driving into opposing or crossing traffic
- Signaling inconsistent with driving actions
- Slow response to traffic signals
- Stopping inappropriately
- Turning abruptly or illegally
- Accelerating or decelerating rapidly
- Driving with headlights off
Surprisingly, speeding is not a clue of insobriety. This is because studies show that a person who speeds often exhibits signs of heightened awareness in the form of quicker judgment and reflexes.