Police officers at DUI checkpoints are trained to look for specific signs of impairment in drivers. These signs can include the smell of alcohol, slurred speech, bloodshot or watery eyes, and difficulty with motor skills. Officers may also observe erratic driving behavior, such as swerving or weaving between lanes. Additionally, they may administer field sobriety tests to assess a driver’s balance, coordination, and ability to follow instructions. If officers have reasonable suspicion that a driver is under the influence, they may request a breathalyzer test to measure blood alcohol concentration. It is important for drivers to cooperate with officers and follow their instructions during DUI checkpoints.