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Are standardized field sobriety tests based upon “junk science”?

Just about any police officer that receives training in Driving Under the Influence (DUI) investigations has been instructed in the use of the standardized field sobriety tests (SFST). Many are familiar with the concept of SFST from Hollywood productions, usually in the comedy genre.

The video, while humorous, does illustrate the supposed evolution of DUI law. At one time, it was the Wild, Wild West when it came to what SFST were administered and how they were conducted and graded. There was nothing to show that the tests proved anything about whether or not the subject was impaired by alcohol, or how the tests should be administered.

There are two different ways to charge DUI, one being actual impairment and the other being driving with a blood alcohol level (BAL) of .08 or greater, without the need to prove impairment. 625 ILCS 5/11-501(a)(1)(2); 625 ILCS 5/11-501.2 There are driver’s license penalties associated with submitting to a breath or blood tests and registering over .08, or refusing to submit. In addition, the results of the test, or a refusal to agree to provide the tests, are admissible in the DUI prosecution. 625 ILCS 5/11-501.2
The field sobriety tests used in the past included reciting the alphabet, finger-to-nose, walk-and-turn (WAT), counting backwards, Romberg, the one-legged-stand (OLS), a portable breath test (PBT) and the Horizontal Gaze Nystagmus (HGN). The National Highway Traffic Safety Administration (NHTSA) claims it commissioned studies that validated the WAT, OLS and HGN as reliable indicators that someone is likely to have a blood alcohol level of .08 or greater, which is the standard in all 50 states, thanks to federal agencies like NHTSA.

So the tests are not designed to detect actual impairment but rather to assess the likelihood that someone is at or above .08. However, the tests are used when the only charge is actual impairment, in other words, in those case where there is no BAC reading.

Some consider the SFST to be “junk science” or in other words, science bought and paid for my NHTSA. Essentially, the argument goes, NHTSA came up with a theory and then paid someone with a scientific background to validate the theory.


Even with all of those advantages, NHTSA itself could only validate that when properly administered, the walk-and-turn test is 68% accurate, and the one-leg stand test is only 65% accurate. The tests were not validated for people with medical conditions, injuries, 65 years or older, and 50 pounds or greater overweight.

The officer waving a pencil in front of the suspect’s face who is instructed to follow it with his eyes performs the HGN. The results of the PBT, or the refusal, are not admissible in the DUI prosecution. 625 ILCS 5/11-501.5
In a DUI trial, the police officer who administered the tests will take the stand and testify about his “training” on the SFST, his experience in DUI arrests and discuss how he administered the tests according to his training. He will not mention the negatives of the test as outlined above, or cast doubt on his testimony that the tests were properly administered, or bring up the fact that the training course he took is something of a joke. Those things are left to the defense to bring out. If they are not, the defendant will be found guilty.

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