Understanding the One Leg Stand Test

This week St. Charles DWI lawyer Todd Ryan provides insight into the One Leg Stand test. The One Leg Stand is the third of the three Standard Field Sobriety Tests (SFSTs) used by law enforcement to determine probable cause to arrest drivers for Driving While Intoxicated (DWI). Similar to the Walk-and-Turn test, the One Leg Stand is a divided attention test with an instruction stage and a performance stage.

On its own, the One Leg Stand test was reported in the 1975 Southern California Research Institute (SCRI) study to be 65% accurate in detecting intoxication. That leaves law enforcement with a 35% error rate. That’s something drivers need to know.
St. Charles DWI Lawyer Todd Ryan
The Missouri Alcohol Influence Report (AIR) gives the investigating officer a series of checkboxes that list the clues the officer is to look for, including: 1) Sways while balancing; 2) Uses arms for balance (raises arms more than 6 inches); 3) Hops; 4) Puts foot down; 5) Cannot perform or refuses to perform the test. The research currently relied on by the National Highway Traffic Safety Administration (NHTSA) suggests that two or more clues or a failure to complete the test indicates a likelihood of a blood alcohol content of 0.08% or greater.

It’s very important for drivers to understand that like the other SFSTs, the One Leg Stand test was developed in laboratory conditions. In particular, the One Leg Stand test is difficult to complete for people who are 65 years or older; have back, leg, or inner ear problems; or are overweight by 50 or more pounds. The research also suggests shoes with heels greater than two inches will invalidate the test results, so drivers should be given an opportunity to remove their shoes. Other environmental factors can cause false positives as well. Extreme cold or heat, slippery or icy surface, uneven surface, and busy or dangerous roadside conditions can affect a person’s ability to complete the One Leg Stand test successfully.

Todd Ryan is amazing! He and his team have helped our family with things a few different times, and we couldn't be more thankful. He knows his stuff and knows how to give advice when you have no idea where to start. He started out as our attorney but quickly became our friend as well!

The law enforcement training manual produced by NHTSA indicates the length of this test is particularly important. NHTSA instructions require the driver to keep his or her foot raised for 30 seconds. The research suggests many impaired individuals can maintain the raised-foot position for 25 seconds but will have difficulty maintaining the position for 30 seconds.

The Ryan Law Firm

415 N. Second St.
St. Charles, Missouri 63301

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