The One Leg Stand (OLS) test is a common field sobriety test used by law enforcement officers to assess an individual’s balance, coordination, and potential impairment due to alcohol or drugs in driving while intoxicated investigations. This non-invasive and easily administered test has gained popularity for its simplicity and reliability in determining an individual’s physical and mental state. In this article, we will explore the purpose, procedure, and significance of the One Leg Stand test in law enforcement and its role in promoting road safety.

Purpose and Background of the One Leg Stand

The primary purpose of the One Leg Stand test is to detect impaired drivers on the roads promptly. Alcohol and drug-impaired driving pose significant risks to public safety, causing numerous accidents, injuries, and fatalities worldwide. To combat this issue, law enforcement agencies have adopted various sobriety tests, with the One Leg Stand test being a crucial component of their arsenal.

The test’s scientific basis lies in assessing a person’s ability to maintain balance and control while standing on one leg. Alcohol and drugs can impair an individual’s motor skills and cognitive functions, making them more susceptible to instability, poor coordination, and reduced reaction times. Therefore, the One Leg Stand test is designed to gauge these attributes, aiding law enforcement officers in making informed decisions about a driver’s sobriety.

Procedure for the One Leg Stand

The One Leg Stand test involves the following procedure:

  1. Instruction: The officer explains the test’s requirements and demonstrates it to the subject.
  2. Stance: The subject is instructed to stand with their feet together and arms down by their sides.
  3. Elevation: They are then asked to raise one leg, typically about six inches off the ground, and keep it parallel to the ground.
  4. Timing: The subject must hold this position for a designated period, often counting aloud for around 30 seconds.
  5. Observations: During the test, the officer observes specific indicators of impairment, such as swaying, hopping, using arms for balance, or putting the raised foot down.
  6. Scoring: Based on the subject’s performance, the officer assigns a score that helps determine the level of impairment.

Significance and Reliability

The One Leg Stand test is considered a valuable tool for law enforcement officers for several reasons:

  1. Portability and Convenience: The test requires minimal equipment and space, making it practical to administer in various roadside situations.
  2. Standardization: Law enforcement agencies often follow standardized guidelines for conducting the One Leg Stand test, ensuring consistency and reliability in its application.
  3. Correlation with Impairment: Research has shown that the test has a strong correlation with alcohol and drug-induced impairment, making it a useful indicator for identifying potentially dangerous drivers.
  4. Field Sobriety Assessment: The One Leg Stand test is part of a battery of field sobriety tests used to gather evidence and establish probable cause for further testing, such as a breathalyzer or blood test.
  5. Objectivity: The test allows officers to observe objective signs of impairment, reducing the influence of subjective biases during the evaluation process.

Challenges and Limitations

While the One Leg Stand test is a valuable tool, it is not without its challenges and limitations:

  1. Physical Factors: Certain individuals, such as the elderly or those with physical disabilities, may find it difficult to perform the test, potentially leading to false conclusions of impairment.
  2. Nervousness: The test can induce anxiety in some individuals, affecting their performance regardless of their sobriety level.
  3. Environmental Conditions: The test’s accuracy can be influenced by external factors such as uneven terrain, adverse weather, or distracting traffic.
  4. Officer Training: The reliability of the test largely depends on the officer’s training and experience in administering and interpreting the results.


The One Leg Stand test serves as a valuable tool for law enforcement officers in identifying potentially impaired drivers and promoting road safety. Its simplicity, portability, and scientific basis make it a practical choice for field sobriety assessment. However, it is essential to acknowledge its limitations and use it in conjunction with other field sobriety tests and chemical tests for a more comprehensive assessment.

As technology and research continue to advance, law enforcement agencies may explore additional methods of evaluating sobriety. Still, the One Leg Stand test remains an essential and well-established component of efforts to combat alcohol and drug-impaired driving on our roads. Ultimately, the goal is to create safer roadways for all users and reduce the devastating impact of impaired driving on society.

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