When police officers notice someone who might be drunk at the wheel, they typically conduct a traffic stop. Pulling someone over allows a police officer to gather evidence and more effectively analyze the situation.
An officer often begins by asking questions about someone’s conduct before the traffic stop. They may then move on to field sobriety testing if someone admitted to drinking or if their responses to questions seem untruthful. Field sobriety tests in theory allow officers to gauge chemical impairment.
How reliable are field sobriety tests as a means of evaluating someone’s impairment?
Even the standardized tests can be inaccurate
Police officers could theoretically be very creative about what tests they ask someone to perform to establish their chemical state. However, creative tests are unlikely to hold up in court proceedings, as attorneys may question the logic or science behind them.
Therefore, the standard procedure for field sobriety testing is to utilize three specific standardized tests recognized as relatively credible. The one-leg stand test requires that a motorist maintain their balance while standing on one leg. The walk-and-turn test involves someone walking in a straight line and then turning to walk back along the same path.
Finally, the horizontal gaze nystagmus test looks at the involuntary muscular movements in the eye. When people look to the side, the muscles in their eyes may twitch involuntarily. Those small motions become much more pronounced when someone is under the influence of alcohol.
In theory, standardized field sobriety tests can be a decent indicator of someone’s chemical state. In practice, there are a host of issues that could compromise the accuracy of field sobriety tests. Drivers might have physical medical conditions that affect their muscular control or balance. They might also have mental health challenges that make them anxious and more likely to stumble or struggle with verbal commands in a high-pressure situation.
Officers can make mistakes when conducting the tests, not the least of which involves the failure to video record the testing process. It is sometimes possible to push back against field sobriety test results as part of a broader drunk driving defense strategy. Reviewing the evidence the state has gathered with the assistance of a skilled legal team can help someone fight drunk driving charges. Those who understand the limits of current testing systems might be able to prove in court that they did not break the law.