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Challenging the One-Leg Stand (OLS) Test in Illinois

The one-leg stand (OLS) test is one of the three field sobriety tests that have been standardized by the National Highway Traffic Safety Administration. As a standardized test, the results from an OLS can be admitted as evidence in Illinois DUI cases. 

Some otherwise law-abiding citizens who have been pulled over and asked to perform an OLS assume that, if they failed it, the state has enough evidence to successfully prosecute. Many alleged DUI offenders may resist the need to fight the charge and instead plea guilty in the hopes they will receive the lightest sentence possible.

Though first-time offenders (as opposed to multiple DUI offenders) will likely receive light sentences unless there are any aggravating circumstances, you still end up with a conviction. That conviction results in a prior that can be used to increase punishment if you are charged with a DUI in the future. That conviction also means a criminal record, and a criminal record can lead to collateral consequences that impact the qualify of your life.

At Dolci & Weiland, we know the risks involved in fighting a DUI charge, but we also know that not fighting means immediate and long-term punishment. It is important to keep in mind that though there is a risk to fighting a DUI, the DUI offense can be successfully challenged. One way to challenge it is to challenge an OLS test. Here's what you should know about the one-leg stand field sobriety test in case you are asked or were asked to perform one in the greater Chicago metro area. 

What is the One-Leg Stand Test?

The one-leg stand is a divided attention test that presents a person with mental and physical tasks. These OLS is meant to determine whether a person is illegally intoxicated to drive a motor vehicle. When a person fails the test, that person allegedly has a blood alcohol content (BAC) level of 0.08%.


The instructions must be given properly and specifically in order for the test results to be admissible in court. The instructions the officer is supposed to give to the alleged DUI offender are as follows:

1. Stand with your heels together and your arms at your side. (Demonstrate)

2. Do not begin until I tell you to.

3. Do you understand?

4. When I tell you, I want you to raise one leg, either leg, approximately six inches off the ground, foot pointed out. Keep both legs straight and keep your eyes on the elevated foot.

5. While holding that position, count out loud; one thousand and one, one thousand and two, one thousand and three, and so forth until told to stop. (Demonstrate raised leg and count) 

6. Do you understand the instructions?

7. You may begin the test.


There are two parts to the OLS test: (1) the instruction phase; and (2) the balance and counting phase. There are a total of four clues that count toward a person's score with two clues established for each phase.

The Instruction Phase Clues (2 total)

  • Swaying while trying to maintain your balance
  • Using arms to balance while the officer provides the instructions

The Balance and Counting Phase Clues (2 total)

  • Hopping while trying to keep your balance
  • Putting a foot down before the test has been completed

If the officer observes two of these four clues, then you are allegedly – according tot he NHTSA – illegally intoxicated with a minimum BAC level of 0.08%.

How can the One-Leg Stand Test be challenged successfully in an Illinois DUI case?

OLS tests can be successfully challenged. If, for example, the test is administered improperly, this alone is sufficient to challenge the results successfully. The police officer administering the test must do it exactly as instructed by the NHTSA. But that isn't the only way to challenge the OLS results. The test is unscientific even if the NHTSA alleges otherwise. There are also a number of other factors that can cause a person to fail the test. 

Unscientific Testing

Created in 1970, the OLS is not based on science. It is a test designed for police officers as an easy way to acquire more DUI arrests. The test itself is only accurate around 83% of the time according to the Validation of the Standardized Field Sobriety Test Battery at BACs Below 0.10%, which – oddly enough – is the test the NHTSA uses to claim the OLS is scientific.

Though 83% is a high percentage, that still leave a window of opportunity open for 17% of DUI arrestees to be falsely arrested. And a DUI arrest alone can cause a lot of pain to a person in terms of loss of reputation, finances, stress, and humiliation.  A person must suffer the latter for a test that was not created using sound science and is not administered by medical professionals who are capable of accurately identifying illegal intoxication as opposed to officer who are capable only of making a good guess. 

Failed Tests Caused by Non-impairment Reasons

There are certain factors that can cause an otherwise unimpaired person to fail a one-leg stand test. Two of the most common include:

  • Surface Conditions. The best conditions that enable a person to successfully perform the one-leg stand include a level ground and non-slippery, hard, and dry surfaces. 
  • Lighting Conditions. On the one hand, there should be adequate lighting so that the alleged DUI offender can perform the test. On the other hand, the sun during the day can be blinding and distracting just as bright lights at night can be.
  • Weather Conditions. Dry weather is the best condition to perform this test. Rain, wind, and snow can distract and affect the alleged DUI offender's performance
  • Traffic Conditions. When the traffic is heavy, it can be both risky and distracting to perform this test near or along the side of the road. The noise can affect the person's ability to hear the instructions and to concentrate on what he or she is doing. This matters because this test is specifically meant to divide the alleged DUI offender's attention and heavy traffic adds another negative dimension to this.

Contact an Experienced DUI Attorney Serving DuPage & Cook Counties

If you have been arrested for a DUI after failing the one-leg stand test, contact the DUI defense attorney at Dolci & Weiland today.