Of the three standardized tests used, the horizontal gaze nystagmus test is the most accurate but even then it is said to be accurate only 77 percent of the time. This test measures the eyeball’s involuntary twitching response to light. The response may be more pronounced after a person has consumed alcohol.
The test with the next highest level of accuracy is the walk and turn test. In this test, drivers are required to walk in a straight line keeping the front heel touching the rear toe while counting. This test is said to be 68-percent accurate. The one-leg test that evaluates a person’s ability to balance on one leg is only 65-percent accurate. When all three tests are used, the overall rate of accuracy is said to be 82 percent.
If you would like to learn more about the tests used by law enforcement during a drunk driving arrest process, please feel free to visit the impaired driving testing page of our Rhode Island criminal defense website.