Police officers trying to determine if someone is under the influence of drugs or alcohol will often start with a field sobriety test. The most common tests performed include the walk-and-turn test, the one-leg stand and the horizontal gaze nystagmus test.
To the average individual, it may seem silly or even sadistic for police officers to have people perform these tests on the side of the road when they suspect drunk driving. However, those field sobriety tests actually fill a very important role in a drunk driving traffic stop. What is the point of a field sobriety test when an officer has access to chemical tests?
An officer needs probable cause to perform a chemical test
Having a driver perform a series of field sobriety tests is actually a necessary step if an officer wants to justify their request for a chemical breath test. Typically, police officers need to have probable cause or sufficient justification to arrest someone for their suspicion of impaired driving if they want to compel that driver to perform a breath test.
The first answers someone gives to initial questions or a few questionable maneuvers at the wheel may not truly be the probable cause an officer needs to justify either a breath test or an immediate arrest. Field sobriety tests help provide additional evidence to confirm an officer’s suspicion that someone is under the influence of alcohol.
Poor performance on any of the tests could give the officer the justification they required to ask for a chemical breath test and then to arrest the driver.
There can be other explanations for field sobriety test issues
Your personal circumstances, ranging from your physical health to your prior interactions with law enforcement professionals, could influence how you perform on a field sobriety test. Medical issues and even extreme nervousness can impact your performance and make you look like you have ingested alcohol or other mind-altering substances when you actually have not.
A thorough analysis of the state’s evidence against you is usually the starting point for any defense strategy when you face allegations of driving under the influence. Educating yourself about how the state builds its case when charging you with a drunk driving offense can help you plan your defense.