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Why do police officers make you perform field sobriety tests?

On Behalf of | Feb 11, 2022 | Drunk Driving

If you admit to having something to drink during a traffic stop or if a police officer suspects you of impairment because of your recent maneuver, they may ask you to perform a field sobriety test. You have to get out of the vehicle and follow the officer’s instructions to demonstrate whether or not you are under the influence of alcohol.

Given that police officers can also perform chemical breath tests, performing a field sobriety test may feel like an embarrassing or degrading demand. Why do police officers ask you to perform physical tasks on the side of the road before asking for a chemical breath test?

They need probable cause for chemical testing

Implied consent laws give police officers the right to require a chemical breath test from any driver for whom they have probable cause to suspect impaired driving. Without an admission of prior alcohol consumption or obvious signs of impairment before the traffic stop, an officer needs to establish probable cause to legitimize their demands for chemical testing.

Your performance on a field sobriety test may give a police officer the justification they need to request a chemical breath test or arrest you. By testing your balance, memory or even your unconscious muscle spasms, an officer can establish probable cause for a chemical testing request.

Are field sobriety tests infallible?

The idea that a police officer can tell from a few moments of physical activity whether or not you are under the influence of alcohol may seem quite suspect. There is science to back the different tests that police officers perform. However, there can be multiple alternative explanations for someone’s subpar performance on a field sobriety test.

In some cases, you may have a medical diagnosis that explains your poor performance on a field sobriety test. Conditions ranging from joint issues to anxiety can affect how you perform in a stressful situation. An officer’s biases can also affect the accuracy of test results. They expect to see signs of impairment, and those expectations will influence their interpretation of your performance.