Are Field Sobriety Tests Accurate? What Drivers Should Know

The Safe Home website reports that in 2024, suspected DUI accounted for 11% of all arrests in the US. That’s 804,926 arrests in total.

Alcohol and drugs can affect the driving abilities of individuals, impairing their thinking and slowing down their reaction. With the use of field sobriety tests (FSTs) in the US, police can determine if a driver is impaired by alcohol or drugs. But can we really trust the result from these tests?

Many factors can affect your performance during that assessment, leading to uncertain results. And comprehending those little subtle details can be crucial if you can go free or be arrested.

Here are the things you need to know about field sobriety tests.

Understanding Field Sobriety Tests: What Are They?

Field sobriety tests (FSTs) are used by law enforcement agents to determine a driver’s impairment. They are designed to determine your coordination, balance, and concentration levels. As such, authorities may ask you to walk in a straight line, stand on one leg and follow a penlight with your eyes.

If you’ve stopped because you’re expected to be impaired, you may not pass the test. You need to prove to the officer that you can drive properly with unclouded judgment. It’s natural to feel stressed during this situation, but you must understand how FSTs work.

How to prepare? Forewarned is forearmed—a little knowledge about what will take place can take away the edge and remind us to try to get through the moment. 

The Science Behind FSTs: Reliability and Validity

It is possible for field sobriety tests (FSTs) to not be as reliable and accurate as they seem when they are not done properly. Most drivers are wrong to think that this is true regardless of any problems that may arise during motility testing. In reality, they are not completely reliable.

Standards will be routinely violated and approved based, in general, on the practitioner’s training in appropriate motor testing and the precise accuracy of the test in the monitored setting. The fact that, despite their careful handling and methodology, these tests are not infallible. 

According to some research-based recommendations, FSTs should be used for results that are only slightly wrong. However, the idea could also be used for people who are supposed to go to trial but instead agree to a plea deal. This can help someone win any future FST disputes in a DUI case, according to DUI lawyer Michael J. Thompson. 

Factors That Affect FST Performance

Field sobriety tests’ performance can be greatly affected by various factors, which in turn reduce the reliability of their results. 

1. Physical condition of the individual. Being tired, anxious, or feeling unwell due to some other reason can make it difficult for you to perform the test properly, regardless of the influence of alcohol. 

2. Weather is another good example, in which difficult circumstances of environmental balance interference have to be kept in mind, such as rain or strong winds with less ability to balance walking. Under such inappropriate weather conditions, control of motor coordination can also be shot, and inner ear issues or sensory-motor deficits could prevent the individual from testing in the right manner. 

3. Age or weight can also impact one’s performance, leading to varied performances based on their comparative level. 

If you recognize these influences, you can understand the potential flaws of FST results.

Common Misconceptions About Field Sobriety Tests

Many people think that field sobriety tests (FSTs) are standard indicators of a driver’s intoxication but that’s not true. 

One common belief is that a failure of the FST signifies legally impaired status. It could very well be other factors causing impairment. Indicating that all law enforcement officers administer the same standardized tests would be pure fantasy. 

Officers need to be trained and educated on the standardized battery of FSTs in order for an FST test result to mean something. We must say that the FSTs are fallible and quite unreliable at times. There is no universal interpretation for these tests; if someone performs poorly on an FST, avoid making assumptions about their impairment. 

Recognizing such misunderstandings may lend one significant serenity and reassure how the person handles a case where an FST is administered. 

What Drivers Should Do If Stopped for Impairment Testing

If you are arrested for a sobriety test, show that you’re not a threat. You may keep your hands on the steering wheel so the officer can see them. Be cooperative towards the officer, but keep in mind your individual rights.

There is no harm in asking whether you are free to leave or being held for different reasons. You could decline to perform a sobriety evaluation since those tests are not fully reliable. If an officer stops you for a ‘mandatory’ test, most people would prefer to say yes rather than no. 

Consider it in light of the fact that declining a breathalyzer test is very likely to be penalized. Being respectful and knowing which rights you have can be of good use in such a period of anxiety.