Understanding field sobriety tests

As is the case anywhere else in the country, Wisconsin law enforcement officers use field sobriety tests as a tool to help determine whether a driver is impaired while driving.

“Failing” these tests supposedly provides the officer with the probable cause needed in order to make an arrest for suspicion of drunk driving. You may wonder what the tests are and what officers are looking for during the testing. Below is a quick explanation that may provide you with useful information should you ever be pulled over and accused of drunk driving.

Test No. 1: The walk-and-turn

This test requires you to walk heel-to-toe and walk approximately nine steps in a straight line, and then do the same thing in reverse. The officer will observe you and look for the following signs of impairment:

  • Needs arms for balance while walking
  • Loses balance while officer gives instructions
  • Loses balance while turning
  • Starts before the completion of the instructions
  • Stops walking to maintain balance
  • Fails to touch heel-to-toe
  • Takes the wrong number of steps

As you can see, balance plays a large role in determining impairment. If you have any issues with your balance, you may fail this test even if you had nothing to drink.

Test No. 2: The horizontal gaze nystagmus

This test observes the involuntary jerking movements your eyes make when you move them. Those movements become exaggerated in intoxicated people. During the test, the officer looks for the following indications of impairment:

  • Distinct jerking at maximum deviation
  • Unable to follow objects smoothly
  • Jerking begins prior to 45 degrees

The problem is that some people fail this test even when sober, due to certain medical conditions.

Test No. 3: The one-leg stand

This test requires you to stand with one leg at least six inches off the ground. You must maintain that stance for 30 seconds while counting out the time, starting with “one-thousand-one.” During that time, the officer observes whether you exhibit the following signs of impairment:

  • Needs arms for balance
  • Sways during the test
  • Puts the foot down
  • Hops to retain balance

Just as in the walk-and-turn test, any number of physical ailments or conditions could cause you to fail this test. In fact, many people have balance issues normally even when they haven’t been drinking.

As you can see, these tests are not a perfect measurement of impairment. If you agree to participate in these tests, you run the risk of failing them, even if you haven’t been drinking. Perhaps the most important fact about field sobriety tests is that you do not have to participate in them. That does not mean that you won’t find yourself under arrest for drunk driving, however. Even so, not taking these tests prevents an officer from using it to establish probable cause for impairment.