To establish probable cause to arrest, the investigating officer will typically employ a battery of standardized field sobriety tests consisting of (1) the horizontal gaze nystagmus test (HGN), (2) the walk-and-turn test, and (3) the one-leg-stand test.
These tests are difficult to perform even if you are sober. However, what is even more unfair is while the investigator will explain, and should demonstrate, how to perform the tests, he or she will not tell you about the clues they look for in determining whether you pass or fail. Beat the Field Sobriety Tests.
For example, when conducting the HGN (nystagmus = involuntary jerking of the eyes, normally almost imperceptible, but exacerbated by elevated levels of blood alcohol), the officer will tell you that he is going to check your eyes. He will instruct you to keep your head still and follow the stimulus (usually a pen), with your eyes only, and to keep focusing on the stimulus until he tells you to stop. He is supposed to hold the stimulus 12-15 inches from your nose.
How Officers Establish Probable Cause
Officers use three clues to tell whether or not you could be intoxicated:
- Lack of smooth pursuit: eyes unable to track stimulus smoothly
- Distinct and sustained nystagmus at maximum deviation: jerking is more pronounced when no white showing in the corner of your eye
- Onset of nystagmus prior to 45 degrees: eyes start jerking before the pen reaches 45 degrees being the starting point straight out in front of your nose
The officer will note whether you can follow instructions — typically whether you're able to remember to keep your head still and follow the stimulus/pen with your eyes only. At the start of the test, he will not tell you that if you fail to do this, he will note it in his report as a sign of impairment.
Walk-and-turn test: When the officer conducts the walk-and-turn test, he will begin with the instructional stage and tell you to place your right foot in front of your left foot, touching heel-to-toe. Keep your arms down at your side. Hold the position until told to begin. He will then move on to the demonstration and walking stage and tell you to take nine heel-to-toe steps down a line (imaginary line if no line exists), turn around, and take nine heel-to-toe steps back. The officer will tell you that when you turn you should keep your front foot on the line and turn by taking a series of small steps with the other foot. When walking, keep your arms down at your sides, watch your feet and count your steps out loud.
The police officer will not tell you that he or she will look for eight clues. Whether you can (1) keep your balance during the instructional stage (whether your feet break apart), (2) start before being told to begin, (3) stop while walking to steady yourself (more than a couple seconds), (4) do not touch heel-to-toe (1/2 inch or more), (5) step off the line (one foot entirely off the line), (6) use your arms to balance (raise one or both more than 6 inches from side), (7) turn improperly (remove both feet from the line), and (8) take incorrect number of steps.
The officer will not tell you that if you exhibit two or more of these clues, he will mark you down as having failed the test!
One-leg-stand test: Like the walk-and-turn test, the officer will start with the instructional stage and tell you to stand with your feet together and your arms down at your side. Do not start until told to begin. He will move to the demonstration and balancing and counting stage by explaining that when he tells you to start to raise one leg, either leg, approximately 6 inches off the ground, toes pointed out. Keep both legs straight, arms at side. While holding that position, count out loud to 30 beginning with “one thousand one, one thousand two, etc.,” until told to stop. Keep your arms at your sides and keep watching your raised foot.
The officer will not tell you that if you exhibit two or more of the following clues, you will fail the test: (1) sway while balancing, (2) use arms for balance (raising them 6 inches or more), (3) hop or (4) put your foot down.
Now that you know what the rules are, you have a better chance of passing the tests or at least understanding what you supposedly did wrong.