A conviction for the offense of driving under the influence in California requires that a prosecutor prove beyond a reasonable doubt that your driving was impaired by the consumption of alcohol. One way an officer who pulls you over on suspicion of DUI will try to establish evidence of your impairment is by administering a series of physical and mental tests, known as roadside field sobriety tests, to determine whether to arrest you for DUI.

Field sobriety tests are used by many police officers and prosecutors as evidence to support DUI cases, despite the fact that they are less than reliable and there are a number of factors affecting a driver’s “failure.” It is important to inform yourself of what these roadside tests are, how they work, and their degree of reliability. This information will be helpful the next time you are pulled over by the police on suspicion of driving under the influence and asked to take field sobriety tests in San Diego.

Roadside Field Sobriety Tests Explained

There are three standard roadside field sobriety tests sanctioned by the National Highway Transportation Safety Administration (NHTSA). The NHTSA is responsible for developing the policy and procedures to be followed by the police in relation to these field sobriety test. Police officers use these three standard tests to determine a driver’s impairment and consequently lay the foundation for a DUI charge.

  • Horizontal Gaze Nystagmus – Nystagmus is the uncontrollable jerking of the eye. In this roadside test, the police officer will use an object and ask the driver to follow that object by looking at it as it moves from left to right.
  • Walk and Turn – Referred to by many as “walking the straight line,” this test seeks to test the mental and physical alertness of the driver. The police will generally ask you to walk heel to toe in nine steps, turn and walk another nine steps.
  • One-Leg Stand – In this test, the police officer will ask you to raise one foot off the ground, hold the position, count to a specific number and look down at your feet.

The objective of all these tests is to determine the impairment of the driver and to ascertain without chemical testing whether the individual is under the influence. Not being able to keep one’s balance or an inability to accomplish both mental and physical activities are all signs a police officer will look for while administering these standardized roadside sobriety tests.

There are some other tests, such as the hand pat or the finger to nose test, which makes up a group of non-standardized tests. They are wholly unreliable but still used by a number of police officers with no real uniformity or procedural accuracy.

Are Roadside Field Sobriety Tests Reliable?

The frequency of their usage and the reliance on the results by law enforcement officers and prosecutors would suggest that roadside field sobriety tests are reliable. However, this is far from the truth.

There are certain conditions that will significantly affect the outcome of the tests and police officers are expected to ensure that the tests are administered under the right conditions.

  • Surface – Surface conditions should not be wet, unleveled, or slippery. Any element of the surface that gives rise to the possibility of you falling are not ideal surface conditions. Additionally, there should be sufficient space to perform the tests, and the police officer is required to find a suitable surface if the one at the point of the traffic stop is not adequate.
  • Lighting – It goes without saying that poor lighting can result in your inability to perform the roadside sobriety test as requested. The police officer can use a flashlight to provide additional lighting in a poorly lit area, but it is best to find an area that is well lit.
  • Ambient Sound – You must be able to hear the instructions since failure to follow the instructions can be deemed a sign of impairment. Loud sounds from traffic or nearby venues can significantly affect your ability to hear the police officer.

Where the conditions are not right, a police officer who proceeds with administering the standardized roadside sobriety tests would be doing so in breach of the established procedure for such tests, and accordingly the results are not reliable.

According to official government studies, even under the right conditions and administered in accordance with the established procedures, standardized field sobriety testing in California is only 77 percent accurate in establishing that a driver has a BAC of .10 or higher. Additionally, the following conditions further weaken the reliability of the tests:

  • Any physical or mental problem being suffered by the driver at the time of the tests that are not related to being intoxicated.
  • Movement by the officer, which will disturb the driver while carrying out the instructions.
  • The attire of the driver, such as wearing heels, can affect his or her ability to complete tests successfully.
  • Unclear instructions from the police officer or failure to administer the test within established procedures.
  • Other factors that may cause loss of balance or inability to perform mental and physical activity that is unrelated to being intoxicated.

The existence of these factors creates a sound foundation for your San Diego dui attorney to get your charges dismissed. Should your DUI matter go to trial, they may also make for a valid defense.

How an Experienced San Diego DUI Lawyer Can Help You

At McElfresh Law, we focus on criminal defense litigation and are very familiar with the different field sobriety tests in San Diego. We understand the law and the legal system and are always ready to fight to secure your freedom. If you have been charged with a DUI offense after a field sobriety test, call McElfresh Law at (858) 756-7107 and let us be your San Diego criminal defense team of choice.

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