If an officer in McKinney, Texas, suspects a drunk driver, the law allows the officer to pull the driver over and conduct field sobriety tests. Research by the National Traffic Highway Safety Administration has concluded that three field tests are the most accurate.
Standard field sobriety tests
When checking for a DWI, an officer commonly uses one of three tests: the walk-and-turn, nystagmus gaze, and the one-leg stand. The walk-and-turn test requires the driver to take nine steps heel-to-toe in a straight line, turn on one leg and repeat. The officer observes whether the driver follows instructions, balances with arms, stops, or loses balance.
The one-leg stand test involves the driver balancing on one leg six inches off the ground for 30 seconds. The officer will instruct the driver to count starting at 1,000 by ones until told to put their foot down. The officer checks for drivers using the arms for balance, putting the foot down before being told to, swaying, or hopping.
The horizontal nystagmus test checks the driver’s vision by having them follow an object, such as a pen. The officer checks for eye jerking at a 45-degree angle, also known as nystagmus, and how smoothly the driver follows the object.
Accuracy of field tests
If a driver fails a set number of clues for each test, the officer may conduct further testing. However, the accuracy of field sobriety tests has been debated because of claims that sober people could fail them in some circumstances.
For example, drivers with back problems, older people, and people with mobility problems can have difficulty performing these tests while sober. The officer should ask the driver if they have contacts or a medical condition and make note of it in their report. High heels, uneven ground, slick surfaces, and tension from the situation can affect a driver’s balance and coordination.
Drivers commonly do not face penalties for refusing field sobriety tests in Texas. If drivers submit to them, there is a chance for errors made by the officer to result in DWI charges.