Officers in Texas often pull suspected drunk drivers over to check them for impairment. They commonly conduct field sobriety tests to gather evidence to use in court. The National Highway Traffic Safety Administration has made three field tests standard.
Standard field sobriety tests
There are three tests the officer commonly uses to check for drunk driving: walk-and-turn, one-leg stand, and horizontal nystagmus. The walk-and-turn test instructs the driver to take nine steps heel-to-toe in a straight line, beginning at the officer’s command. Once they complete nine steps, they turn on one leg and repeat the other way, while the officer watches for cues.
During the horizontal nystagmus gaze test, the driver follows an object with their eyes, such as a pen. The officer checks for three cues between each eye, which are smooth following, involuntary blinking at 45 degrees, and maximum deviation. Maximum deviation is blinking that occurs within four seconds after the eye has turned completely to the side.
The one-leg stand test requires the driver to raise one leg off the ground and balance for 30 seconds. The officer checks for swaying, hopping, putting the foot down early, and balancing with the arms.
Why sober drivers may fail
Many sober drivers fail these tests. Several factors can cause this to happen, including age, weight, test environment, weather, and medical issues. For example, sober drivers with back and leg problems or inner ear issues may fail the walk-and-turn test.
Officers must also follow the NHTSA instructions to score tests correctly and stay updated on training to avoid inaccuracy. If the driver is wearing heels over two inches, the officer should allow the driver to remove them.
Drivers may commonly refuse to take field sobriety tests without penalty. If they have taken the tests and failed, they can challenge the accuracy with valid defenses.