During any Driving While Intoxicated or Driving Under the Influence stops, it is likely you will find the Police Officers attempting to administer some form of the Standardized Field Sobriety Test. These tests, which are intended to ascertain whether the subject is impaired by alcohol or some other impairing substance, vary slightly in which ones are used by which jurisdictions. However, the main tests are almost always the same.

These test were created by The National Highway Traffic Safety Administration. Each test carries with it a percentage of successfully identifying impairment in the test subject. No one test is 100% accurate.

The three common used (and are the three primary tests used where I practice North Carolina DWI Defense) are the One-legged Stand, the Walk-and-Turn, and the Horizontal Gaze Nystagmus test. Below is a brief, and not complete, description of each test.

During the One-Legged Stand test, the subject is requested to stand with one foot elevated roughly 6 to 8 inches off the ground, keeping their hands at their sides, and stare at their extended foot while they count outloud 'one-one thousand, two-one thousand...' until they reach 30. The Officer is looking to see if the subject sways, steps down early, or uses their arms for balance.

For the Walk-and-Turn Test, the subject is asked to stand heel-to-toe, while instructions are given. The subject is then asked to proceed to walk a straight line (sometimes there is an actual line, sometimes there isn't), making heel-to-toe contact on each step for a certain number of steps (9 in North Carolina) then turn and do the steps back. The subject is asked to stare at their feet during their steps, count out loud each step, and keep their hands at their side. The Officer is looking for whether the subject starts early, steps off line, fails to make heel-to-toe contact, turn incorrectly, miscount, or not complete the test.

Finally, the Horizontal Gaze Nystagmus test is where the officer asks the subject to keep their head straight while following a finger or pen as they move it left and right and up and down. Contrary to a common misconception, this test is not looking to detect whether you can perform the test without moving your head (though it will likely be noted if you do so). Actually, the test is looking to detect what is called Nystagmus. Nystagmus is the involuntary 'jerking' of the eye at certain points during the test that is suppose to be indicative of impairment. For that reason, only the Officer knows whether you failed the test or not.

Each of these tests come with them a guidelines that must be adhered to while the administering the test or their results may be inadmissible in court. If you are facing a DWI or DUI charge, it is important to discuss your case with a DWI attorney. They can best advise you as to the strengths and weaknesses of your case.