The National Highway Traffic Safety Administration has guidelines for three types of field sobriety tests. According to the NHTSA, law enforcement members in New York and across the country are trained to use these tests when they suspect someone of drunk driving. Those tests include the following:
- The walk-and-turn: A suspect is required to walk heel-to-toe in a straight line for nine steps, turn around, and walk back.
- Eye testing: Officers look for an involuntary jerking of the eye that, in inebriated individuals, happens in an exaggerated manner.
- The one-legged stand: The suspect must stand on one foot for 30 seconds while the officer looks for swaying, hopping and using arms for balance.
The NHTSA reports that 79 percent of people who have trouble with at least two of these tests have an illegal blood alcohol concentration. That leaves plenty of room for falsely accusing people of DUI, especially because these tests are subjective rather than fact-based.
One of the biggest factors that can affect someone's performance on a field sobriety test is a medical condition. As a report from the State Bar of Michigan notes, people who have middle ear or back problems will likely have difficulty standing on one leg, which could further law enforcement's suspicion of DUI.
Additionally, there are a number of environmental factors that could lead to an inaccurate test. For example, extreme temperatures may detract from a driver's focus during the testing. Roads that are uneven - which are common - can be problematic during the walk-and-turn and one-legged stand.
Drivers in New York are permitted to refuse field sobriety tests. This is especially helpful when motorists believe they would perform poorly and give the prosecution evidence against them.