You may not believe it, but the fact is that many sober individuals are falsely accused of being intoxicated because they fail field sobriety tests. Field sobriety tests are just one indication of a person's abilities, and they shouldn't be the only factor involved in an arrest.
Field sobriety tests include the one-leg stand, walk-and-turn and horizontal gaze nystagmus test. Each test has its benefits. For instance, the HGN can identify people who can't focus or who have trouble following the movement of the officer's light or finger. A one-leg stand can show if a person is unbalanced. A walk-and-turn test can show if a person can walk well unaided.
The problem with the tests is that completely sober individuals can fail them. It's particularly common among older individuals and those with medical conditions. For example, someone having a medical emergency could be misidentified as being drunk. When pulled over, the person may be unable to walk well or focus for the HGN test. Usually, it takes only a matter of time before the medical emergency is recognized, but by then, an arrest may already be on the person's record.
It's important to seek a breath test instead of a field test if you have the ability to do so. Field sobriety tests are open to interpretation, and that's the last thing you want working against you in court. If you've failed one and weren't intoxicated at the time, it's a good idea to talk to someone familiar with the law and to get help having the case dismissed or dropped.
Source: Alcohol Problems and Solutions, "Failed Field Sobriety Test Happens to Sober Drivers Often," accessed Feb. 08, 2018