Standardized field sobriety tests – What are they?

Horizontal gaze nystagmus

The HGN test is the most accurate of the three tests.  The test has a 77% accuracy rate in detecting when blood alcohol levels are above .10%.  Nystagmus itself is involuntary jerking or bouncing of the eyeball.  The jerking or bouncing makes it appear that the pupil is being pulled back towards the center of the eye opening.

A few things cause nystagmus, the most relevant in this case being alcohol use.  Certain other drugs that depress the central nervous system also cause nystagmus.  These substances make it more difficult for the brain to properly control the eye muscles.  As the concentration of specific drugs or alcohol increase in the body, the most obvious the nystagmus becomes.

The test is conducted by an officer who positions an object, usually a pen or a finger, a foot away from the driver’s face.  The officer then moves the object from one side to the other while focusing on the driver’s eye movements.  If jerking occurs before the officer reaches a 45-degree angle, it indicates a possible blood alcohol content above .05%.

A few of the biggest complaints about the HGN test are based on the fact that police officers are not medically trained professionals.  They also often fail to properly conduct the test, which results in a flawed test result.

Walk and turn test

The walk and turn tests, when administered properly, is 68% accurate in identifying blood alcohol content levels of .10% and above.  The walk and turn test is relatively simple and is comprised of two parts.

The first part of the test begins before the driver even beings the walk and turn.  The officer instructs the driver to stand in an instructional pose – the driver is instructed to stand with one foot in front of the other in a straight line, with the heel or one foot touching the toes of another.  If the driver fails to follow officer instructions, such as standing in a “normal” pose or by beginning the test early, it is counted as the first sign the individual may be intoxicated.

Walk and turn part two

The second part of the test is when the actual walking begins.  During the first part, the officer had already demonstrated how the driver is to walk along the straight line.  The officer tells the driver to take nine heel-to-toe steps down the line.  After the ninth step, the driver must turn around by taking a series of small steps and return to the starting place by taking another nine heel-to-toe steps.  While making each of the nine steps, the driver is instructed to count each step out loud.

There are a few clues that the officer looks to in the walk and turn test.  Again, starting early or breaking the instructional stance is one.  An inability to stay balanced during instruction is another.  Failure to touch heel-to-toe, stepping off the line, using arms to balance, an improper turn, or making the incorrect number of steps are all clues to intoxication that occur during the test.

The test needs to be performed on a dry and level area to prevent the surface from interfering with the test.  This is one of the ways officers fail to conduct the test appropriately.  As you know, Wisconsin winters can be long and snowy, and roads are often full of salt.  That could be a problem.  Wearing heels?  If your heels are over two inches, you should be allowed to remove them.

One-leg stand

The one-leg stand test is third of the standardized field sobriety test battery.  It’s the least accurate of the field sobriety tests in this article.  When conducted properly it’s 65% accurate in determining whether the driver’s blood-alcohol content is above .10%.

This test is also the most simple, but it’s important the officer properly instructs the driver.  The officer, during the instructional phase, tells the driver to stand with his feet together and arms at his sides.  Often this is when the officer demonstrates the test.  Then, the officer tells the driver to keep his arms at his sides and raise his leg approximately 6 inches off the ground.  While keeping his leg raised, the officer requests the driver begin counting upwards from one thousand.

The officer looks for four clues during this test.  They include:

• Swaying while balancing;
• Using arms to balance;
• Hopping with one foot to maintain balance; and
• Resting with a raised foot on the ground.

Just like the walk and turn test, law enforcement should require you to complete this test on dry, hard, and level land.  Again, if you’re wearing heels, law enforcements should allow you to remove them.

What’s next?

Creators of field sobriety tests designed them for drivers to fail.  Once the driver is to the point of actually doing the tests, the law enforcement officer has likely already made up his decision to arrest.  If you succeed, law enforcement will likely release you.  Upon a failure, law enforcement will probably require you to complete a preliminary breath test (PBT).  If the preliminary breath test comes back at or above a .08 (.02 in some cases), you will be arrested for OWI.

Contact our drunk driving defense lawyers for help with your case.

After an arrest for drunk driving, you’re likely wondering what the next step is.  Our drunk driving defense attorneys believe that hiring a top attorney to help you is the wisest way to proceed.  From that point we can guide you through the various steps of the case.  It’s also when we’ll determine whether there are any pre-trial motions to file in your case.  At that point we can also discuss your right to trial.

Contact Van Severen Law Office at (414) 270-0202 to begin discussing you drunk driving case.  We understand that frequently OWI arrests occur at night and on the weekends.  For that reason, we answer phones 24/7.  Contact us today and let’s start fighting your case.

A criminal defense attorney updated this blog post on July 13, 2020.