During the one-leg stand test, the officer will direct the driver to stand with feet together and arms down while the officer delivers the test instructions.  The officer will tell the driver to raise one leg about six inches, with the foot parallel to the ground. The driver will be told to look at his or her foot while counting “one thousand one, one thousand two …” until told to stop.  The driver must stand on one leg for 30 seconds.

The officer is looking for four signs of impairment – swaying while balancing, using the arms to balance, hopping on one foot, and putting his or her foot down three or more time during the test. If the officer sees two or more of these signs, he or she will conclude that the driver has a blood alcohol content (BAC) of .10 or greater, and the driver will be arrested for DUI / DWI.

This test presupposes that an individual would be able to perform this test sober – many people have trouble standing on one leg for 30 seconds, whether or not they’ve had a few drinks.  Although the prosecution will attempt to use the results of this test to demonstrate physical and mental impairment due to being under the influence, this isn’t necessarily so.  The one-leg stand test is especially challenging for people with back or leg injuries, individuals with inner-ear disorders or other balance problems, people over 65, and those who are overweight. Uneven ground or shoes with heels higher than two inches can add to the challenge.

Remember, the results of a field sobriety test are based upon the police officer’s subjective opinions.  A California criminal defense lawyer skilled in defending drunk driving cases can challenge an officer’s evaluation and demonstrate that a driver’s performance in the one-leg stand test and other field sobriety exercises could just as easily show that the driver was not impaired.