The One Leg Stand test is usually the third test that an officer will administer to a suspect that the officer believes is impaired by alcohol. What the officer is looking for is the suspect’s ability to divide his or her attention and still perform a set of tasks as instructed. There are two phases of the test. In each phase the officer is tasked with certain responsibilities and the suspect is given certain objectives. The officer is looking for “clues” of impairment. In the One Leg Stand test there are four possible clues of impairment. If the suspect exhibits two clues then the test results indicate that the person is impaired. The two phases are below.

Instructional Phase:What the officer is supposed to do: The officer is supposed to give instructions on how to complete the test and demonstrate the proper way to perform the test. The officer should also make sure that the testing site is appropriate. The officer should give the following instructions:

  1. Please stand with your feet together and your arms down at the sides;
  2. The officer should give a demonstration standing feet together and arms at his or her sides;
  3. Do not begin the test until told to do so;
  4. The officer should ask the suspect if he or she understands;
  5. After the suspect is placed with their feet together and arms to the side and confirmed that they understand the instructions, the officer will tell suspect that when the officer tells the suspect to begin the test, the suspect should raise either leg off the ground with the foot approximately 6 inches off the ground.
  6. The officer will instruct the suspect to keep their legs straight and their arms at their sides for the duration of the test.
  7. While holding that position, count out loud in the following manner: “one thousand one, one thousand two, one thousand three,” and so on until told to stop.
  8. The officer will tell the suspect to “keep watching their raised foot.”
  9. The officer will ask if the suspect understands the instructions as given.
  10. If the suspect responds that they understand, the officer will tell the suspect to begin the test.

What the suspect is supposed to do: At this point the suspect does not need to do anything other than listen to the officer and not start the test until asked to do so. The suspect cannot display a clue during the instructional phase.

What Clues the officer is looking for: There are no clues that the officer can negatively score a suspect for during the instructional phase of the one leg stand test. However, that will not stop an officer from recording in his or her report that the suspect is swaying, failing to maintain balance, slurring their speech, et. cetra.

Common mistakes officers make: Improperly scoring a “failure to maintain balance while listening to the instructions.” clue: This happens often among officers that are not experienced with DUI investigations. This clue is not a clue at all in the context of the One Leg Stand test. This is only a clue when administering the Walk and Turn test. Often a poorly trained officer will assess this clue.

Improperly scoring a clue for “beginning the test to early”: Again this happens when an officer has little experience with DUI investigations or was poorly trained. Beginning the test too early is not a clue for the One Leg Stand test. It is only clue when administering the Walk and Turn test.

Giving incorrect instructions: Officers will give confusing or altogether incorrect instruction on the One Leg Stand test. The most common mistake officers make is forgetting to ask the suspect if they understand the instructions. If an officer forgets to ask the suspect if they understand the instructions the entire test comes into question.

Balance and Counting Stage:What the officer is supposed to do: The officer is supposed to be watching the suspect for clues of impairment and simultaneously keeping time for the test. The officer is supposed to also determine if what he is seeing is a clue of impairment or the suspect’s performance on the test is due to some other environmental factor.

What the suspect is supposed to do: The suspect has a difficult task. The suspect must remember and perform the set of instructions as the officer told them to. The suspect is also under added stress of being in an adversarial situation and unfamiliar location.

What clues the officer is looking for: The officer is looking for four different clues, each is open to interpretation and subjective.

  1. Sways While Balancing- This refers to the side to side or back and forth motion while the suspect maintains the one leg stand position. Slight tremors of the foot or body should not be interpreted as swaying. (NHTSA Participant Manual 2013, Section 8, Page 51 of 62)
  2. Uses Arms to Balance- If the suspect moves their arms to balance or extends their arms out to maintain balance then this clue should be scored. The suspect must move their arms 6 or more inches from the side of the body in order to keep balance before this clue can be scored. (NHTSA Participant Manual 2013, Section 8, Page 51 of 62)
  3. Hopping- This refers to when the suspect is able to keep one foot off the ground, but resorts to hopping in order to maintain balance.
  4. Puts foot down- If the suspect is not able to maintain the One Leg Stand position, putting their foot down one or more times during the test counts as one clue.

Common Mistakes Officers Make:Conducting the Test in an inappropriate location: The One Leg Stand test should be conducted on a dry, hard, and non-slippery surface. The subject’s safety should be considered at all times. If there is no available testing cite then the officer should not conduct the test at all. (NHTSA Participant Manual 2013, Section 8, Page 49 of 62)

Failure to Keep Time: The One Leg Stand test is supposed to be conducted for thirty seconds. An officer will seldom tell the suspect that the test is supposed to be for thirty seconds and is not required to. The officer is supposed to use a timing device to keep track of the time. If the officer does not keep accurate time he is in violation of the NHTSA manual. (NHTSA Participant Manual 2013, Section 8, Page 52 of 62)

Giving Instruction During the Performance of the Test: Officers forget that one of the most important parts of the Standard Field Sobriety Tests is the first word, “Standard.” The test is standardized; it must be given the same way every time if the officer intends to rely on the perceived results. The officer is not authorized to instruct a suspect while they are taking the test. For example, an officer cannot tell the suspect to make sure to “count out loud” if the suspect stops counting. If an officer does this, then the officer is introducing an additional stimulus to the test. Therefore, making the test more complicated and invalidating the results. The only time this is acceptable during the One Leg Stand test is if the suspect puts his foot down. Then and only then may the officer instruct the person to pick their foot back up. (NHTSA Participant Manual 2013, Section 8, Page 52 of 62)

The Suspect’s Age: If the suspect is over the age of 65 the research indicates that the suspect will have difficulty with the test regardless of their consumption of alcohol. (2013 Participant Manual Session 8, Page 49 of 62). An officer should not administer the SFST battery to an individual over the age of 65.

The Suspect’s Weight: If the suspect is 50 pounds overweight the research indicates that the suspect will have difficulty with the test regardless of their consumption of alcohol. (2013 Participant Manual Session 8, Page 49 of 62). An officer should not administer the SFST battery to an individual whom is 50 pounds’ overweight.

The Suspect’s Physical Condition: If the suspect has back, leg, or inner ear problems the suspect will have difficulty with the test regardless of their consumption of alcohol. (2013 Participant Manual Session 8, Page 49 of 62). An officer should not administer the SFST battery to an individual with those physical problems.

The Suspect’s footwear: If a suspect is wearing heels more than 2 inches high they should be given the opportunity to remove their shoes when performing the SFST battery. (2013 Participant Manual Session 8, Page 49 of 62) If an officer fails to give the suspect the option to remove their heels the officer is operating outside of the NHTSA guidelines.

Problems with the One Leg Stand TestOfficer Mistakes: As you can see above there are ample opportunities for an officer to make a mistake in either instructing the suspect on how to perform the test or make a mistake on how to interpret the results of the test. In all aspects of field sobriety testing these two problems are by far and away the most common reasons that people get falsely accused of DUI.

Reliability: There are Four studies and one data point that are cited to back up the One Leg Stand Test

Data Point: The National Highway Traffic Safety Administration Participant Manual cites “recent research” that indicates an accuracy of 83% for the One Leg Stand test. (2013 Participant Manual Session 8, Page 53 of 62).

Southern California Research Institute StudyThe original research conducted by the Southern California Research Institute that was used to develop the Standard Field Sobriety Test curriculum indicated that the One Leg Stand test was 65% accurate at detecting subjects at or above a .10 BAC. This study is aimed at detecting an alcohol concentration that is higher than the legal limit. It was performed nearly 40 years ago and has an abysmal accuracy rating. (This study is not available online)

Validation of SFST at BAC below 0.10 (San Diego Study)This study was finalized in 1998. It is a relatively small sample size of 297 motorists. The study claims an 83% accuracy rate for arrests decisions based on the One Leg Stand test.

(Click to see the San Diego SFST Study)

A Colorado Validation Study of the SFST Battery.This study was finalized in 1995. This study had a sample size of 305 participants. The study claims an 86% accuracy when administering all three tests.

(Click to see the Colorado SFST Study)

A Florida Validation Study of the SFST Battery.

This study was finalized in 1997. This study had a sample size of 256 breath tests. The study claims an 95% accuracy when administering all three tests.

(Click to see the Florida SFST Study)