The Standardized Field Sobriety Test battery consists of three tests: The One-Leg Stand, the Walk and Turn and the Horizontal Gaze Nystagmus tests.
If a law enforcement officer stops you on suspicion of driving under the influence (DUI) of alcohol, you could actually be sober and still fail the field sobriety tests.
Conditions are not ideal
Most field sobriety testing occurs at the side of the road. So, to begin with, the conditions are not ideal. The ground may be uneven, adversely impacting both the One-Leg Stand and the Walk and Turn. Passing traffic may be a distraction and anxiety may affect your ability to perform the tests well.
Reasons for refusal
You may have back, leg or foot issues that would make two of the three tests difficult for you. Low blood pressure, an ear infection, a head injury or even the medications you take may cause balance problems. Height, weight and circulation issues can cause you to fail the field sobriety tests. No one over the age of 65 or more than 50 pounds overweight should agree to take these tests.
The reason for this kind of testing is to provide a law enforcement officer with just cause to arrest the suspected drunk driver. However, the grading of the field sobriety tests is subjective. Two officers looking at a video of the same test may disagree about the score. Keep in mind that the tests are between 65% and 80% reliable. If you were sober when taking the tests, a successful defense will highlight any discrepancies and errors that occurred and provide you with the best outcome possible for your case.