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How do sobriety tests determine a driver’s condition?

On Behalf of | Feb 26, 2024 | DUI

The police use several methods of collecting evidence when it’s suspected that a driver is drunk or violating traffic laws. A driver may be questioned about their condition, for example. Or, the police may notice an open bottle of alcohol or bills in a driver’s vehicle. 

If the police can not collect enough evidence with questions alone, they may ask a driver to do a field or chemical sobriety test. Here’s what the police can find with both tests: 

Using field sobriety tests to find signs of inebriation

A field sobriety test is a physical examination that helps the police spot signs of inebriation. The National Highway Traffic Safety Administration has three types of standardized field sobriety tests. Here’s what you should know about each:

  • Horizontal gaze nystagmus test: The police can spot signs of inebriation by spotting flickering movements in a driver’s eyes. 
  • Walk-and-turn test: A driver may appear inebriated if they stumble or fall during this test. 
  • One-legged stand test: Falling over, putting a foot down or losing balance may be indications of inebriation during this test.

These tests are not always accurate. If a driver has medical conditions or takes medication, then the police may mistakenly consider a driver drunk.

Using chemical sobriety tests to evaluate a driver’s BAC

Chemical sobriety tests evaluate the amount of alcohol found in a driver’s blood, which is also called the blood alcohol content (BAC). A driver may be asked to take a blood, breath or urine test. Drivers may refuse a chemical sobriety test. However, refusal of a post-arrest chemical sobriety test can lead to severe criminal consequences. 

Further guidance may be necessary if you believe your legal rights were violated during a traffic stop.