We all know that there are multiple ways of testing for drunk driving, and it’s fairly clear what is involved in a breathalyzer or urine test. However, the other form of testing for intoxication is the field sobriety test, and it’s not so obvious what is involved in that. Whether you have never been pulled over and just want to be informed in the event that you are, or you have been charged with driving while intoxicated and you want to make sure that your test was conducted correctly, read on for a breakdown of field sobriety test basics.
The National Highway Traffic Safety Administration and the Southern California Research Institute have come up with three primary components of a field sobriety test.
- The Horizontal Gaze Nystagmus (HGN) Test measures the involuntary eye twitches that you have when intoxicated. Nystagmus is a normal ocular movement that usually occurs when the eye is rolled up to a high angle. However, when you are drunk, nystagmus is more pronounced and occurs when your eye is looking in a lower angle. To measure nystagmus, a police officer will ask you to track his finger, a pen, or a small light with your eyes while he watches for unnatural movements. If your eye moves erratically, or if you are unable to track the object, you will likely be arrested for drunk driving.
However, the test is only 88% accurate, and there are hundreds of causes of nystagmus that have nothing to do with drinking.
- In the Walk-and-Turn Test, an officer will ask you to take nine steps in a straight line, walking heel-to-toe. Once you have reached the end of the line, you will need to turn on one foot and walk back along the line in the same way. The officer looks at your ability to stay balanced, follow directions, and count steps. It is particularly difficult to follow multiple directions when you are intoxicated.
The test is supposed to be 79% accurate, which still leaves a fairly wide margin of error.
- In the One Leg Stand, an officer will ask you to stand on one foot and count out loud for 30 seconds. The officer looks to see if you sway, put your foot down, use your arms to balance, or hop on one foot. This is the most accurate of the three tests with an 83% accuracy rate.
There are several other tests an officer may give, including the finger tap test, finger to nose test, and Rhomberg Balance Test. While most of these tests are considered valid in court, they are easier to contest, so they are less common. The three common tests are much more convincing in court; however, each one has a wide margin of error, so if you fail one of the three methods, it is important that you obtain good legal counsel who can help you find any inaccuracies in the testing.