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One Leg Stand (OLS)

California Highway Patrol Officers and other DUI law enforcement officers administer the One Leg Stand or OLS as one of the three Standardized Field Sobriety Tests (SFST's) during a DUI investigation. The One Leg Stand is not a pass or fail test. Rather, performance on the "test" is scored. The test is a balance and coordination test. Additionally, officers testifying in DUI Hearings and DUI Trials contend it is a divided attention test and a test of following directions.

The One Leg Stand should be given on level ground, on a hard, dry, non-slippery surface, and under conditions in which the DUI suspect will be in no danger should he or she fall. If these guidelines cannot be followed at the place where you stop the driver, you may be able to move to a better location. As noted above, the One Leg Stand test consists of an instructional phase, demonstration phase and performance phase. Proper environmental conditions include a reasonably dry, hard, level and non-slippery surface.

Instructional Phase

The One Leg Stand usually follows the Horizontal Gaze Nystagmus (HGN) eye examination. The officer is required to give instructions which are to be followed by a demonstration of the One Leg Stand Field Sobriety Test. Following the instructions and demonstration, the officer is supposed to ask the driver under investigation if the instructions are understood.

Performance Phase

The performance phase of the One Leg Stand requires the driver to raise either leg approximately six inches off the ground with the foot pointed out. Both legs are to be kept straight with arms at the side. The driver is to count "one thousand and one, one thousand and two, one thousand and three" while looking at the raised foot until told to stop by the officer. The officer is to continue the test for thirty seconds regardless of what number the driver has reached in counting.

Scoring Performance

The below listed clues are most likely to be present in a driver having a blood alcohol level of 0.10 percent or higher. Four or more cues will result in the officer rendering the opinion that the driver was possibly under the influence.

  • Sways while balancing.
  • Uses their arms for balance, raising them six or more inches from the side of the body
  • Hops
  • Puts foot down one or more times during the 30 second count

If the driver is unable to perform the One Leg Stand or puts their foot down three or more times, the officer is to record all four clues were observed. Time is considered to be critical in scoring this test. The National Highway Traffic Safety Administration (NHTSA) DUI Enforcement Manual represents the One Leg Stand is an accurate predictor of a person having a blood alcohol level of 0.10 percent when all four clues are present.

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