When a police officer stops a driver suspected consuming alcohol, the officer requests that the driver perform certain physical tests.

The Standard Field Sobriety Tests (SFST)

The National Highway Traffic Safety Administration (NHTSA) is part of the U.S. Department of Transportation. The NHTSA has developed a set of tests that, it claims, can determine the extent to which a person is affected by the consumption of alcohol. Maryland police officers typically use these “Standard Field Sobriety Tests” consisting of:


  • the “walk-and-turn” test
  • one-leg stand test and
  • horizontal haze nystagmus test.

The premise of the tests is that alcohol inhibits muscle coordination. If someone suspected of alcohol consumption fails the tests, the presumption is that alcohol caused the failure.

The SFST’s as Evidence

Reinforcing this presumption is the police officer’s training. The typical experiment is in a classroom filled with police officers. Volunteers perform the SFST and take a drink. They repeat this process and, over the course of several drinks, they naturally demonstrate their diminishing ability to perform the tests. The officers can then observe how the performance of the tests declines with the increase of alcohol consumption.

At trial, the police officer can testify, without a hint of doubt, that the consumption of alcohol deprived the driver of the coordination to drive.

My job is to negate the efficacy of the tests as well as their relevance.