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Do Field Sobriety Tests Actually Work?

Ever since the 1970’s, law enforcement officers have been administering the three “standardized” field sobriety tests (FSTs)—the walk-and-turn, one-leg stand, and horizontal gaze nystagmus—to determine whether a driver has operated their vehicle while intoxicated. A driver’s performance on these tests is meant to indicate whether the individual has a BAC of .08% or more, acting as a basis of an officer’s probable cause for a DUI arrest.

Alas, the reliability of these test results is often questioned.

How Reliable Are These Tests?

The National Highway Traffic Safety Administration (NHTSA) performed a number of studies where officers gave FSTs to people with known BACs. The main goal was to figure out how well officers could identify a person with a BAC of .1% or higher

According to the results of these tests, studies showed officers could correctly identify these drunk drivers:

  • 80% of the time using multiple FSTs
  • 77% of the time using the horizontal gaze nystagmus test only
  • 68% of the time using walk-and-turn test only
  • 65% of the time using the one-leg stand only

Scientists will contend that the accuracy of these tests does not support the reliability of standardized FSTs. For example, when these tests are correct, they only indicate BAC level, not a person’s ability to operate a vehicle.

Challenging Field Sobriety Tests

Criminal defense attorneys and expert witnesses who study FSTs understand their flaws. Any individual arrested for DUI on the basis of an FST score is encouraged to challenge these results in an effort to either get your entire case dismissed or your charges reduced significantly.

Recently arrested for a DUI in Ventura County, CA? Contact our Ventura DUI attorney at The Law Offices of Robert F. Sommers and request a free consultation today.