Most people know that if a police officer pulls over a suspected drunk driver, they are likely to give them a field sobriety test. Pop culture has depicted this in several ways; sometimes the suspect must walk in a straight line, sometimes they must recite the alphabet backwards.

The reality is that police have a series of standardized tests they administer. The problem with these tests is that they often yield false positives, even for sober people. This means that someone may fail the test and be arrested whether they were truly over the limit or not.

If you find yourself facing DUI charges, do not hesitate to enlist legal representation. Even when evidence looks bad, there is always hope. A professional attorney will look at all the facts and fight to defend your rights and freedom.

These are the 3 standardized field sobriety tests used by law enforcement, according to the National Highway Traffic Safety Administration, and ways someone who is not over the legal limit may still fail.

Horizontal gaze nystagmus (HGN)

Possibly the least known field sobriety test, in the horizontal gaze test the officer will sweep their finger back and forth and ask the suspect to follow the tip with their eyes. When intoxicated, a person’s eyes will involuntarily move in a more jerky or exaggerated manner.

The environment can diminish the accuracy of this test. The officer must be able to see the suspect’s eyes clearly, something that is difficult at night. If it is night, oncoming headlights, the officer’s flashlight or the flashing lights of the police cruiser can also conflict with the results.

Walk and turn test

The classic “walk the line” sobriety test. In the walk and turn (WAT) test, the suspect is asked to walk nine heel-to-toe steps, counting each step as they do so, turn on their heel, then walk back – all while keeping their hands at their sides and their head down. The officer will be looking for wobbling, stepping from the line, not walking heel to toe and pretty much anything else that’s suspicious.

The problem with this test is that many people innately have balance issues, whether it be from illness, disability or exhaustion. Anxiety of being under the scrutiny of a police officer may also lead to a failing grade.

One-leg stand test

In this test the officer will ask the suspect to count to thirty while standing with one foot 6 inches off the ground with their hands at their sides and looking forward the entire time. If the suspect wobbles, puts their arms out, puts their foot down or otherwise tries to adjust their balance, it is most likely a fail.

This is a highly disputed test since it may be difficult for a sober person to pass in perfect conditions. Remember that this test is often administered at night, in the glare of headlights and cruiser lights, while other cars are passing at a high rate of speed and potentially on uneven, gravel strewn ground; conditions that could throw anyone’s balance off. Additionally, overweight individuals may have difficulty standing on one foot for 30 seconds while completely sober.

If you find yourself unable to make the grade on one of these tests, don’t be afraid to fight the charges. Many argue that field sobriety tests have been designed for suspects to fail. While there is not definitive answer to that, the fact is that they are not 100 percent accurate.