When police officers suspect someone of alcohol impairment, they need to gather evidence. The prosecutor needs proof beyond a reasonable doubt that someone had impaired ability or was over the legal limit for their blood alcohol concentration (BAC).
Video footage from a cruiser of someone swerving or their involvement in a crash is not conclusive proof of intoxication. There can be reasonable alternate explanations for both scenarios. Police officers need to establish that intoxication is the underlying cause of someone’s diminished ability or the crash that occurred.
Field sobriety testing often plays an important role in that process. What typically transpires during field sobriety testing?
Officers have drivers exit their vehicles
An officer requesting that a motorist exit their vehicle likely either wants to conduct a physical search of their person or intends to request field sobriety testing. They typically need to have the drivers stand someplace with proper illumination so that either the dashboard camera in their cruiser or their body camera can capture footage of the field sobriety test.
The officer then guides the motorist through a series of three standardized tests and records any personal observations that may indicate alcohol impairment. They may arrest someone after the tests or use them as a justification to request a chemical test.
The tests administered are not always accurate
The three standardized field sobriety tests are an important part of drunk driving traffic stops because they provide the most reliable evidence of impaired physical ability. There are numerous alternate explanations for why a driver might perform poorly on any of those other tests. Both the walk-and-turn test and the one-leg stand test look at someone’s ability to focus and their coordination. Motorists may have medical conditions that affect their behavior or their motor function.
The horizontal gaze nystagmus test involves using the eyes to follow a moving object without turning the head. Officers watch for signs of an involuntary muscle spasm that becomes more pronounced after alcohol consumption. There can be alternate explanations for an exaggerated twitch in the eye muscles just like there are alternate reasons that people might not be able to balance on one leg or walk in a straight line.
Ultimately, field sobriety testing is fallible and may give officers a false sense of confidence when they determine that someone is under the influence. Drivers typically have the option of refusing field sobriety testing after a crash or during a traffic stop. They may also be able to defend against charges based in no small part on the outcome of field sobriety tests.
Understanding how the state develops a drunk driving case can be beneficial for those hoping to avoid a criminal conviction. Field sobriety tests are often a key component of the state’s case, and defendants can use that information to plan a viable defense strategy.
