Field sobriety tests involve a series of physical activities to test your balance, coordination and ability to follow directions, all of which the consumption of a few drinks will compromise. The National Highway Traffic Safety Administration has standardized three components of the FST, citing studies that show how reliable they are for validating the intoxication of a driver. However, many variables may render the results of the test invalid.
How reliable are FSTs?
When an officer presents the results of an FST to the court, it often carries a lot of weight. Studies show that, 90 percent of the time, FSTs validate the reading of a BAC test when a trained officer administers the test appropriately. This may be the first crucial variable. How well trained was the officer, and how accurately did he or she administer the test?
The three tests that make up the standardized FST are these:
- The horizontal gaze nystagmus tests the involuntary jerking of your eyes, which the consumption of alcohol exacerbates.
- The walk and turn test evaluates how easily you can walk heel-to-toe without losing your balance.
- The one-leg stand test also measures your ability to maintain your balance.
All of these tests also include the element of following numerous instructions at once, such as taking the correct number of steps before turning or counting by thousands as the officer directs you to do.
Factors that affect the results
Unlike a blood alcohol test, the law does not require you to submit to FSTs. It is your right to politely refuse. However, if an officer has asked you to step out of the car and stand on one foot, he or she probably already has enough probable cause to make the arrest.
While the tests are supposedly standardized, each person and situation is different, meaning there is often little about an FST that is standard. The environment, the uneven terrain, level of noise and your own physical health are important factors in your ability to pass the tests. Additionally, the results of the test are often subjective, based on the observations of the officer who has likely already decided that you display signs of intoxication.