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Why do police officers request that people perform field sobriety tests?

On Behalf of | Oct 1, 2023 | DUI & Traffic Defense |

One of the most stressful occurrences during an Illinois traffic stop involves a police officer asking a motorist to exit the vehicle. At that point, the driver probably knows they will need to perform field sobriety tests.

People worry about the embarrassment that comes from performing physical tests on a roadside to allow an officer to evaluate them for chemical intoxication. They may feel as though the intention of such testing is specifically to make them feel humiliated.

Why do officers make people perform physical tests when they suspect someone of intoxication at the wheel?

Officers need probable cause for the next step

Maybe the officer began suspecting intoxication watched someone swerve from side to side as they drove. As soon as they approach the vehicle, they will likely ask questions about whether someone had anything to drink. Other times, it might be the conversation during the traffic stop that makes the officer think someone is under the influence. They may slur their speech or admit to having a few beers earlier in the evening.

Despite having a vague suspicion, an officer cannot arrest someone right away for impairment. They need probable cause or a confession to arrest someone. A field sobriety test allows them to gather evidence that could produce the probable cause they need to take the next step. The decision to administer the three standardized field sobriety tests can justify an officer’s subsequent demand for a chemical breath test.

If someone can’t walk in a straight line or balance on one leg, that could be a sign of intoxication. Officers could also arrest someone because of how their eyes move while following an officer’s finger from side to side without moving their head. Poor performance on field sobriety tests is often a key element of a drunk driving case.

As someone arrested when they were not drunk might already realize, field sobriety tests are far from infallible. Numerous physical and psychological mental health conditions could lead to someone’s poor performance on such tests. Some individuals accused of drunk driving in Illinois can raise questions about the accuracy of the field sobriety test that they performed. Others may work with a lawyer who will question the legality of the traffic stop and therefore the ability of the state to use field sobriety test results and other evidence gathered during the traffic stop in a criminal trial.

Understanding the systems that the state uses to build a criminal case can help someone more effectively develop a defense strategy when accused of drunk driving or similar offenses. Seeking legal guidance is a good way to gain this clarity.