This is usually the third test an officer will administer to a person they believe is impaired by alcohol. The officer is looking for their ability to divide their attention while still performing the instructed sets of tasks. The test has two phases and in each phase the officer has certain duties and the individual has certain objectives. Officers are looking for “clues” of impairment. This test has four possible clues and if a person exhibits two of these, it will indicate they are impaired. The two phases are discussed below:

Instructional Phase:

What the officer is supposed to do: Law enforcement is supposed to demonstrate the proper way to perform the test and give instructions on how the suspect is to complete the test. Further, the officer shall make sure the testing site is proper. The instructions which should be given are:

  1. Stand with your feet together and arms at your sides;
  2. Officer should demonstrate #1;
  3. Don’t start the test until instructed to do so;
  4. Officer should ask individual if they understand;
  5. After suspect is in proper starting position and affirms they understand the instructions, the officer will say when they are allowed to begin the test, the suspect should raise the leg of their choosing off of the ground with their foot approximately 6 inches off of the ground.
  6. Officer will instruct them to keep their arms at their sides and their legs straight the entire test duration.
  7. When holding this position, count aloud in the following way: “one thousand one, one thousand two, one thousand three,” and so on until told to stop.
  8. The officer will instruct the suspect to “keep watching their raised foot.”
  9. The officer will again ask if the suspect understands the instructions.
  10. If the suspect answers in the affirmative, the officer will instruct them to start the test.

What the suspect is supposed to do: They only need to listen to the officer and don’t prematurely start the test. They should not display a clue during this phase.

What clues the officer is looking for: During this phase, an officer cannot negatively clue a suspect. However, they can still put in their report that the individual failed to maintain balance, swayed, slurred their speech, etc.

Common mistakes officers make:

Improperly scoring a “failure to maintain balance while listening to the instructions.” Clue: This generally happens with officers who are inexperienced with investigating DUIs. This clue is not valid in the context of this test. It is only a clue during the Walk and Turn test. Usually a poorly trained officer will report this clue.

Improperly scoring a clue for “beginning the test too early”: This is not a clue for this test, only the Walk and Turn test. Again, usually this happens when the officer is inexperienced or poorly trained.

Giving incorrect instructions: Sometimes an officer will give incorrect or confusing instructions. The most common mistake is not asking if the suspect understands the instructions. If they forget to do this, it can bring the entire test into question.

Balance and Counting Stage:

What the officer is supposed to do: The officer will be simultaneously be keeping time for the test and watching the individual for any clues of impairment. They should also determine if some other factor is the reason for the clue rather than impairment.

What the suspect is supposed to do: The individual performing this test has a difficult task. They are being asked to remember and perform the officer’s instructions. They are also under additional stress of being in an unfamiliar location while in an adversarial situation.

What clues the officer is looking for: There are four clues that the police will be looking for, each of which is subjective.

  1. Swaying While Balancing- this is referring to the back and forth or side to side motion while the individual is in the one leg stand position. Minor tremors of the body or foot shouldn’t be interpreted as swaying. (NHTSA Participant Manual 2013, Section 8, Page 51 of 62)
  2. Using Arms to Balance- this clue is scored if the individual moves their arm to keep balance or extends their arms outwards to maintain balance. In order for this clue to be score, the movement must be 6 inches or more from the side of the individual’s body. (NHTSA Participant Manual 2013, Section 8, Page 51 of 62)
  3. Hopping- This is when a person hops in order to keep balance.
  4. Putting Foot Down- Putting your foot down one or more times while performing this test will count as a clue.

Common Mistakes Officers Make:

Test conducted in inappropriate location: This test should be conducted on a hard, dry, and non-slippery surface. The individual’s safety needs to be considered at all times. The officer shall not administer the test if an appropriate cite is not available. (NHTSA Participant Manual 2013, Section 8, Page 49 of 62)

Failure to Keep Time: This test should be conducted for thirty seconds. The officer is not required to inform the individual of this and they seldom do. If the officer does not keep accurate time via a timing device, they are in violation of the NHTSA manual. (NHTSA Participant manual 2013, Section 8, Page 52 of 62)

Giving Instructions During the Performance of the Test: The first word of the Standard Field Sobriety Tests is “standard” and it happens to be one of the more important parts. These tests are standardized and should be given the same way every time if law enforcement wants to rely on their results. Officers are not permitted to instruct individuals while they are performing the tests. For example, if an individual stops counting aloud and an officer reminds them to do so, they have thus introduced an additional stimulus to the test. This added stimulus makes the test more complicated and invalidates the results. The only time an officer can re-instruct an individual during the test and not invalidate the results if is the individual puts their foot down and the officer tells them to pick it back up. (NHTSA Participant Manual 2013, Section 8, Page 52 of 62)

Suspect’s Age: Research has shown that a person over 65 years old will have difficulty with this test regardless of their alcohol consumption. (NHTSA Participant Manual 2013, Section 8, page 49 of 62) Officers should not administer this test to someone over 65.

Suspect’s Weight: Research has shown that a person who is 50 pounds overweight will have difficulty with this test regardless of their alcohol consumption. (NHTSA Participant Manual 2013, Section 8, Page 49 of 62) Officer should not administer this test to someone who is 50 pounds overweight.

Suspect’s Physical Condition: Individuals who have back, leg, or inner ear problems will have difficulty with this test regardless of their alcohol consumption. (NHTSA Participant Manual 2013, Session 8, Page 49 of 62) Officers should not administer this test to someone with these physical problems.

Suspect’s Footwear: An individual wearing heels more than 2 inches high should be given the chance to remove their shoes when performing the SFSTs. (NHTSA Participant Manual 2013, Section 8, Page 49 of 62) If an officer fails to give the individual an opportunity to remove their shoes, they are in violation of the NHTSA guidelines.

Problems with the One Leg Stand Test

Officer Mistakes: As discussed above, there are numerous opportunities for an officer to make a mistake either instructing the test or interpreting the results. These are the two most common ways individuals get falsely accused of a DUI.

Reliability: There is one data point and four studies with back up this test.

Data Point: the NHTSA manual cites “recent research” with claims an 83% accuracy for this test. (2013 Participant Manual Session 8, Page 53 of 62).

Southern California Research Institute Study: This was the original research used to develop the SFSTs and it indicated this test had a 65% accuracy at detecting an individual at or above a .10BAC. This study is aimed at recognizing a BAC which is higher than the current legal limit of 0.08%. This study is also over 40 years old and has a terrible accuracy rating. (It is no available to view online)

Sand Diego Study: This study was in 1998, had a sample size of 297 motorists, and claims arrests based on this test have an 83% accuracy rating.

Colorado Validation Study of the SFST Battery: This study was in 1995, had a sample size of 305 participants, and claims there is an 86% accuracy when all three tests are administered.

Florida Validation Study of the SFST Battery: This study was in 1998, had a sample size of 256 breath tests, and claims an 95% accuracy when all three tests are administered.