Driving behaviors that indicate a lack of concentration or control are often interpreted as signs of impairment. For example, taking turns too widely, failing to stop at intersections, drifting between lanes, inappropriate slowing or stopping, seemingly random changes in speed or operating a vehicle at night without headlights. Police also look for anything wrong with your car, like missing license plates, expired registration, or inoperable rear lights, which then give them a basis to stop your vehicle and check for alcohol or drug consumption.