How do Standard Field Sobriety Tests work (and don’t work)?

Just about everyone has heard of field sobriety tests that police administer to people they suspect of impairment during a traffic stop. You may be among those here in Colorado and elsewhere who think these tests are simply to determine whether or not a person is safe to drive.

During field sobriety tests, a person suspected of driving while impaired or intoxicated will be asked to perform certain actions for the police to observe. Some people may believe that they can fool the police or beat the test somehow with good balance or intense focus, but what police are doing is more subtle than that. Your actual performance on the test may not matter at all.

What is the Standard Field Sobriety Test?

Three tests  make up the standard field sobriety tests. These tests are standardized by the National Highway Traffic Safety Administration (NHTSA). They are:

• The one leg stand test — You must stand on one foot and count out loud for around 30 seconds without losing your balance, hopping, putting your foot down, or using your arms to balance.
• The walk and turn test — You must take nine heel-to-toe steps in a straight line, turn around and take nine heel-to-toe steps in the opposite direction, but only when the officer says to do so. If you lose your balance at any point, stop walking, use your arms or don’t take the right number of steps, that is considered inconsistent with how a sober person would perform.
• The horizontal gaze nystagmus test — You must follow a point with only your eyes while the officer checks to see if your eyes begin jerking prior to when they might in a sober person.

If the officer believes your performance on any of these tests was consistent with impairment or intoxication, you could find yourself required to to a blood or breath test, and could ultimately find yourself under arrest. These tests are subjective, and any number of things could skew them. An officer who already suspects you of impairment or intoxication will not give you the benefit of the doubt. If you have a physical illness or condition that affects your ability to successfully complete these tests, the officer could still consider your performance on the tests a basis for believing that there is probable cause sufficient to require you to participate in a blood or breath test.

If you participated in these tests and the officer claims you “failed” them, it does not necessarily guarantee a conviction. You may challenge the validity of the tests, along with all of the other circumstances surrounding your arrest. A Boulder DUI defense attorney can help.