Are field sobriety tests accurate?

Are field sobriety tests accurate?

On Behalf of | Jun 23, 2022 | DUI/DWI

There are three standardized field sobriety tests approved for use by the National Highway Traffic Safety Administration.

Most Massachusetts residents may well have heard reports about how a driver was arrested for and charged with a drunk driving offense after failing field sobriety tests. But, not all people may actually really know what these tests are, what they are supposed to measure and whether or not they are fully accurate. provided reports like this on at least two occasions recently. In May, a man was arrested in Stoughton and according to sources he failed multiple field sobriety tests. Another driver was arrested in June and sources in that case only reference one field sobriety test.

The Chelsea Record tells of how officers stopped a driver who reportedly failed to stay in his lane. They administered one field test per the story and after the driver’s failure of the test he was arrested.

Tests do not measure intoxication

According to, the tests used by law enforcement officers at the scene of a potential impaired driving stop are not intended to prove that a person is intoxicated. Instead they are meant to give officers enough evidence to suggest that a person might be intoxicated, thereby giving law enforcement probable cause with which to support an arrest.

Three tests approved by government

The National Highway Traffic Safety Administration has authorized three different standardized tests. Law enforcement agencies are encouraged to use all three, despite the fact that some reports like those referenced above refer to only one test being used. The tests are supposed to be administered according to very specific instructions as well.

Accuracy rates are not high

Individually the three tests have accuracy rates of 65 percent for the one-leg stand test, 66 percent for the walk-and-turn test and 77 percent for the eye test. If all three tests are administered, the overall accurate rate is said to go up only to 82 percent.

Many things may interfere with test accuracy including medical conditions that might prevent a driver from being able to balance on one foot. People who have inner ear conditions, hip problems, excessive weight and more may all find this very difficult even if they had not been drinking.

Shoes and road conditions may also make it hard for someone to pass these tests. Finally, most people are likely to be very nervous and scared when being tested by officers and this may also hinder their ability to balance or execute multiple tasks at one time without error.

Legal help after a drunk driving arrest is important

People who have been charged with operating under the influence in Massachusetts should contact a lawyer as soon as possible. Getting the help of someone who understands the nuances of the laws and the tests used during the arrest process may give defendants the information they need for their defense.