One-leg Stand Test

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Drivers under investigation for DUI / DWI in California typically take a field sobriety test, such as the One-leg Stand Test, during a traffic stop. The One-leg Stand Test is one of three field sobriety tests standardized by the National Highway Traffic Safety Administration (NHTSA).

Unfortunately, police officers don’t use the One-leg Stand Test to determine whether a driver is impaired; they are used to justify an arrest and gather evidence for a court case. A knowledgeable DUI / DWI criminal defense attorney can effectively challenge the results of the One-leg Stand Test as part of an aggressive drunk driving defense.

The One-leg Stand Test is a divided-attention test. It purportedly assesses mental and physical impairment from alcohol intoxication by requiring drivers to focus on two tasks at once. Police and prosecutors routinely ignore everything drivers do correctly and focus on even insignificant errors as evidence of alcohol impairment.

When administering the One-leg Stand Test , an officer directs the driver to stand with arms down and feet together during the test instructions. The officer then instructs the driver to raise one leg six inches off the ground, keeping the foot parallel to the roadway. The driver is told look at his or her foot while counting “one thousand one, one thousand two…” until told to stop, typically for 30 seconds.

Police watch for four signs of impairment: Swaying, using the arms to balance, hopping on one foot, and/or lowering the foot three or more times during the test. If the officer spots two or more of these signs, he or she will presume that the driver has a blood alcohol content (BAC) of .10 or greater, and the motorist will be arrested for DUI / DWI.

Police and prosecutors regard field sobriety test results as solid evidence of intoxication, but the results of the One-leg Stand Test can be successfully challenged. To understand how this evidence can be challenged, it’s useful to know how alcohol affects the human body.

When an individual drinks alcohol, mental impairment always occurs before physical impairment. Individuals with a high tolerance for alcohol can mask physical impairment, but mental impairment cannot be disguised. If no mental impairment can be proven, then any physical impairment must be attributed to factors other than alcohol.

In order to convict a driver of DUI / DWI, the prosecutor must present evidence of both mental and physical impairment. The physical impairment displayed in the One-leg Stand Test can be attributed to sources other than alcohol, such as injury or illness. A skilled DUI / DWI attorney can prove that there are many reasons other than alcohol impairment why a driver might perform poorly on the One-leg Stand Test .

Even people who haven’t had a single drink might have difficulty standing on one leg for 30 seconds. The One-leg Stand Test is especially difficult for drivers with back or leg injuries, individuals with inner-ear disorders or other balance problems, people over age 65, and individuals who are overweight. Drivers who perform the test on uneven ground or who are wearing shoes with heels higher than two inches also face challenges.

Because field sobriety tests are extremely subjective, they can be effectively challenged in court. A California defense lawyer who focuses on drunk driving defense will show that the driver’s performance in the One-leg Stand Test and other field sobriety exercises can be attributed to many factors other than alcohol intoxication.