The One Leg Stand is one of three standard field sobriety tests (FSTs) used by law enforcement officials in Minnesota and throughout the country to gauge whether or not an individual suspected of DWI might be impaired under the influence of alcohol.
During the One Leg Stand or OLS, a driver is asked to stand still with both feet together, and arms placed at the sides. The driver will then have to stand on one leg of their choice while counting aloud to about 30 seconds, with the other foot approximately six inches off the ground. If the driver struggles in this position, then the officer may assume that his or her blood alcohol content level is above the legal limit.
According to the National Highway Traffic Safety Administration, the One Leg Stand has an accuracy rating of 65 percent. When combined with the walk-and-turn test, another FST, reliability is roughly 80 percent. This test is referred to as a “divided attention test”, as it asks an individual to divide his or her attention between one physical task, and one mental task.
When a driver is asked to perform an OLS, he or she must remember that this FST cannot just be performed anywhere. Certain conditions must be met. While this test is often conducted roadside, it may also be conducted at another location, or even at the police station if there is probable cause for arrest. The test however, should only be conducted on a hard, level, dry, and non-slippery surface, and in a location where the suspect is in no danger if he or she were to lose their balance and fall.
The FST should also be conducted in an illuminated area. Even the most sober of individuals may have difficulty performing the One Leg Stand in darkness.
A suspect wearing high heels, or shoes with two-inch heels or higher, should be allowed to remove those shoes and perform the test barefoot. The police officer should also inquire about any injuries that may hamper his or her ability to balance on one leg.
When grading a suspect’s OLS, officers follow a scoring system comprised of five components. The following will be taken into consideration:
- Swaying back and forth or side to side while balancing
- Using arms for balance and raising them more than six inches away from the leg
- Hopping on one foot in order to maintain balance
- Putting his or her foot down at least once while counting to 30
- Not being able to perform the test. If the suspect puts down his or her foot three times or more throughout the OLS, this will indicate that he or she cannot perform the test.
Of course, there have been numerous instances of people failing the One Leg Stand – without being impaired. Several factors may cause a sober driver to appear uncoordinated – such as age, weight, illnesses, confusion, stress, fatigue, medications, and even fear of a police officer.
In other scenarios, poor lighting and weather conditions are also factors. Roughly 90 percent of DWI arrests take place at night, and since officers are trained to shine their flashlights on the ground near the suspects feet for illumination purposes, the moving light may actually disorient the drivers. Strong winds may also cause someone to lose his or her sense of balance.
Although the OLS may indicate alcohol impairment, it can never establish an individual’s BAC on its own. More information is needed, and other FSTs, chemical blood tests or breath machine tests must also be performed before an individual can be properly convicted of DWI.
Source: “One-Leg Stand Test”, published at http://www.fieldsobrietytests.org/onelegstandtest.html.