Can You Pass Colorado DUI Field Sobriety Tests?

When you are stopped and contacted by a police officer for a DUI investigation, one of the first things that will be requested of you is roadside tests, or field sobriety tests. Once the officer that pulled you over or otherwise contacted you runs your driver’s license and calls for a cover officer, he or she will ask you to get out of your car and perform field sobriety tests. The law states that these tests are voluntary, but sometimes officers do not convey this important point to you. If an officer does not tell you that these tests are voluntary, you should let your DUI attorney know so he or she can properly address the issue.

The National Highway and Traffic Safety Administration (NHTSA) recommend three roadside DUI tests. They are the Horizontal Gaze Nystagmus test (HGN), the Walk-and-Turn test, and the One-Leg-Stand test. Both the Walk-and-Turn and One-Leg-Stand are called “divided attention tasks” that require a driver to listen to, watch, and follow instructions while at the same time performing a physical task.

Horizontal Gaze Nystagmus

“Nystagmus” is a term used to describe involuntary eye movement. There are several types of nystagmus, as well as several medical conditions and environmental situations that can cause it. Alcohol consumption is one of the many causes. Alcohol is a central nervous system depressant that affects motor coordination and reflexes. When a person is under the influence, his or her nervous system will cause the eyes not to move smoothly. Individuals may display this “jerking” in their eyes when intoxicated by alcohol.

When conducting the HGN test, the DUI officer will instruct you to remove your glasses or your hard contact lenses. Then the police officer will tell you he or she is going to check your eyes. You are then told to keep your head still and follow an object, such as a finger or pen, with your eyes. The officer will then observe both eyes while moving the stimulus horizontally in front of your face to see whether there is any jerking or un-smooth tracking in ether or both eyes. The officer checks for three conditions in each eye: lack of smooth pursuit, distinct and sustained nystagmus at maximum deviation, and onset of nystagmus prior to 45 degrees. The federal government, through NHTSA, claims that based on its tests in the 1970s and 1980s, a person has a 77 percent probability of having a BAC of 0.10 or higher when exhibiting all six clues.

As noted above, medical conditions and environmental circumstances can cause an officer to mistakenly interpret eye movement as being caused by alcohol. Seizure medications and other drugs, head injuries, and flashing lights (like the ones on top of a police cruiser) can affect eye movement or the appearance of eye movement that mimics nystagmus. There are multiple causes of nystagmus and conditions that mimic this observation, so it is important to be represented by an experienced DUI attorney who understands the HGN test and the various conditions that could affect the officer’s observations.


The Walk-and-Turn test involves a DUI suspect standing with one foot immediately in front of the other, and then walking heel-to-toe for nine steps down and back in a straight line. At the mid-point of the walk and turn test, the officer will instruct the suspect to make a pivoting turn-around.

The DUI officer will instruct you to place your left foot on the line, and then the right foot on the line ahead of the left foot, with the heel of the right foot against toe of the left foot. Also, you are instructed to place your arms down to your sides and maintain this position until the police officer completes the instructions. At this point, the officer is supposed to demonstrate part of the test, as well as how to perform the halfway turn. While walking, you are told to keep your arms to the side, watch your feet at all times, and count your steps aloud.

The officer is trained to score the Walk-and-Turn test based on the following criteria:

  • Can you keep his or her balance while listening to instructions?
  • Did you start too soon?
  • Did driver stop while walking?
  • Did you not touch heel-to-toe?
  • Did you step off the line?
  • Did you use his or her arms to balance?
  • Did you make a proper turn?
  • Did you take the correct number of steps?

There are many factors can influence a person’s performance on the Walk-and-Turn other than alcohol or drug consumption. This physical test requires a straight line and should be conducted on a reasonably dry, hard, level, non-slippery surface. Given the stressful situation that a motorist is out in by being asked or requested to do roadside tests, combined with the temperature and environment on a potentially unsafe, sloped, or slippery surface, it is no wonder sober drivers often cannot pass this test. In addition, footwear can affect your performance, as it is much easier to walk in tennis shoes than high heels. Finally, NHTSA-sponsored research has concluded that persons at sixty-five years of age or older, or persons with back, leg, or middle ear problems may have difficulty performing this test. Given all of the extenuating factors that can come into play, your performance on the Walk and Turn test can be challenged.


The One-Leg-Stand test requires a DUI suspect to stand on one leg with his or her arms to the side with a raised foot while counting aloud for thirty seconds. Like the Walk-and-Turn test, the One-Leg-Stand is a divided-attention test, requiring you to be able to listen to and follow instructions while at the same time performing the physical maneuver—balancing on one foot while listening to the officer’s instructions.

When starting this test, the officer instructs you to stand with your feet together and arms down to your sides. The officer will then tell you to raise either leg with the foot approximately six inches off the ground and to keep the foot parallel to the ground. The DUI officer should also demonstrate this action. The officer will tell you that you must keep both legs straight and arms to the side, and while holding this position, count out loud in the following manner: “one thousand and one, one thousand and two, one thousand and three, etc.,” until told to stop.

The officer is trained to make the following observations while you are performing the One-Leg-Stand test:

  • Did you sway while balancing?
  • Did you use your arms for balance?
  • Did you hop?
  • Did you put your foot down?

Just like other roadside DUI tests, the One-Leg Stand requires a reasonably dry, hard, level, and non-slippery surface. Also, older individuals, people with back or leg problems, or overweight individuals may have issues performing this test. In addition, the stress of the situation and the outside environmental conditions could have an effect on your performance.

Your performance on these field sobriety tests is a critical part of your Colorado DUI case. Before going to court, be sure to discuss your performance and the external influences with your Denver DUI attorney that could have influenced the officer’s decision to arrest and charge you with Driving Under the Influence.

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