Field Sobriety Tests

Field Sobriety Tests

Even if you have never been pulled over by the police for suspicion of drunk driving, you are probably aware of what commonly happens to those who are. The officer will come up to your window, ask for your license and registration, and discreetly slip into a less formal conversation. If you're ever in this situation, it's important that you limit the extent to which you engage in conversation. Generally, the police aren't that interested in where you are going or where you are coming from, except if you just came from a tavern. These questions are designed to get drivers to talk more and reveal tell-tale signs of intoxication. If they are not completely satisfied that you are sober, they may ask you to “voluntarily” take some field sobriety tests.

The first thing to remember about field sobriety tests is that they are voluntary. Because they are designed to gather evidence of a crime – the crime of driving under the influence of intoxicants (DUII) – they are considered a “search” under the Oregon Constitution and the U.S. Constitution. Both of these Constitutions prohibit “unreasonable” searches. In order for a search to be “reasonable,” the police either need to have a warrant, or the search would have to fall within a certain set of exceptions to the warrant requirement. One of these exceptions to the warrant requirement is if you consent to the search – if you agree to let the search happen, then you are saying that you will not exercise your Constitutional right to refuse a warrantless search.

Which brings us to the second thing to remember about field sobriety tests; While the police assume that the tests will give them evidence that you are driving drunk, they can also give solid evidence that you are sober.

While these two things about field sobriety tests are important to keep in mind, they only help you before you have been pulled over. If you have already been pulled over, subjected to field sobriety tests, arrested and charged for DUII, it might seem like a lost cause. This is not the case. In my 20+  years defending against DUII charges, I know just how prone to error these tests are, and I and show it in a persuasive way to a jury. .

Here are two of the field sobriety tests that Oregon police use, together with how they often produce false positives and other inaccurate results.

Horizontal Gaze Nystagmus

One of the most common field sobriety tests used, the Horizontal Gaze Nystagmus is designed to detect involuntary eye movement that commonly occurs after drinking alcohol. In the test, the police officer will hold up a pen, or a finger, about twelve to fifteen inches in front of your nose. While you hold your head still, the officer will move the pen to the side and into your peripheral vision, to see if your eyes can smoothly track the motion.

Data collected by the National Highway Transportation Safety Administration (NHTSA) determined that the test was the most accurate of all the tests in determining if you have any alcohol in your blood system.


In the Walk-and-Turn, a cop will ask you to walk a line, putting the heel of one foot to the toes of the other foot, rather than typical steps, all while holding your hands at your sides, looking at your feet, and counting the steps. They will then have you turn at the end of the line, and walk back.

The Walk-and-Turn tests your ability to multitask, as well as your balance. Police watch for eight clues that indicate intoxication:

  • Inability to keep balance,
  • Beginning before the instructions are finished,
  • Stopping while walking the line, in order to regain balance,
  • Not touching your heel to your opposite toe,
  • Stepping off the line,
  • Raising your arms more than six inches from your sides,
  • At the end of the line, turning differently than the way the officer instructed,
  • Taking an incorrect number of steps

Showing two of these things means that you fail the test. Most sober people will show two or more clues.

One Leg Stand

The last test that is usually given is called the one leg stand. The officer will have you stand with your feet together and hands to your side. The officer will tell you that when he tells you, life a leg of your choise, six inches off the ground, with both legs straight. You will be told to count out loud by thousands until you are told to stop. You

Other field sobriety tests have similar holes in them. In my years defending against DUII charges, we have seen very few people not “fail” the field sobriety tests, even those with zero alcohol and zero drugs in their system. You are keep your hands to your sides and look down at your raised foot. The test is supposed to last 30 seconds. The things that the officer is looking for is if you hop, sway, put your foot down or raise a hand from your side more that six inches. Do two of those things, and you have lost.  

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