Can sobriety tests measure impairment?

On Behalf of | Aug 12, 2020 | Drunk Driving |

After going through the experience of a DUI traffic stop, you might question how doing physical activities road can determine one’s impairment level. The truth is sometimes judges throw out the results of these tests because they aren’t always black and white.

Unlike a blood alcohol concentration (BAC) level, there isn’t a number attached to one’s performance on standard field sobriety tests. Rather, it’s up to the police officer administering the test to decide whether the suspect is showing signs of impairment or not.

Here are some common tests and signs that the driver might be under the influence of a substance:

  • One-leg stand test: Subjects taking this test must stand up, hold one foot up nearly six inches above the ground and count from 1,000. The officer will note if the suspect puts their foot down too soon, loses balance or tries to keep balance by hoping or moving their arms.
  • Horizontal gaze nystagmus test: Through this test, the suspect must follow a moving object with only their eyes. If they look away from the object or their eyes jerk involuntarily, then the officer might write these off as signs of impairment.
  • Walk-and-turn test: During this test, the suspect must walk in a straight line and take heel-to-toe steps. Then, they will turn around and take nine more steps in the opposite direction. Like the one-leg stand, one sign of impairment may include loss of balance. Taking the correct number of steps and touching one’s heel to their toe are also important steps to follow to steer clear from a DUI charge.

Having some alcohol, drugs or a combination of the two within your system can cause you to have a hard time focusing on the task at-hand or impact your coordination. But sometimes, there are ways this test might not be accurately depict impairment, like side effects of legal, prescription medications or health conditions that might impact someone’s ability to balance. And, in some cases, if a subject doesn’t follow the instructions properly, it might be because of unclear instructions in the first place.

Furthermore, there is research to show that while these tests might indicate a suspect’s BAC level, there still isn’t concrete evidence to show how failure of these tests equate to inability to operate a car. Since a sober person could ultimately fail a sobriety test, it’s crucial to consult a legal expert before your court date.