If the police have ever pulled you over on suspicion of drinking and driving, you likely have undergone field sobriety tests before. If not, you probably are familiar with them anyway: the walk-and-turn test, eye movement test, one-leg balance test and others are supposed to help the officer prove whether the driver is over the legal limit or not.
But just because law enforcement in San Jose and across the country has used field sobriety tests for decades, it does not mean they are highly accurate or foolproof. In fact, experts regularly criticize these tests for being unscientific and unreliable indicators of somebody’s sobriety. Here are three reasons why.
Lack of baseline
Most of the time, the officer and driver have never met before. The officer has no idea what the driver’s performance on field sobriety tests would be when they are in normal conditions. Without anything to compare to, the officer can only guess that the driver’s performance is being affected by alcohol and not some extenuating circumstance.
Disability can affect performance
One such circumstance that has nothing to do with alcohol is disability. Many drivers in San Jose have one or more conditions that affect their balance, coordination and ability to stand and walk. Some of these conditions are not immediately obvious but are very real. So can mental conditions like anxiety or simple nervousness about being stopped by the police and possibly getting arrested.
Also, the horizontal gaze nystagmus test, which looks for jerks in the motion of the eyes as they move side to side, can be misleading. Several neurological conditions cause jerking but do not impair one’s driving ability.
The tests are subjective
Unlike a properly administered breath or blood test, field sobriety tests do not produce an objective measurement of alcohol in the driver’s system. The officer administering the tests must rely on their judgment and experience to come up with the answer. You could end up arrested based in part on “failed” tests that you did not actually fail.
Remember, no matter what the officer says or implies, you do not have to consent to field sobriety testing in California.