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What Are DUI Field Sobriety Tests

Last year, there were an estimated 214,828 drunk driving arrests in California alone. During a DUI stop, something that determines whether or not the driver will be arrested is alcohol testing. A driver can be arrested if an officer judges that the driver seems to be intoxicated (through field sobriety tests) or if the driver’s blood alcohol content (BAC) is over the legal limit or .08%. If a person has been charged with driving under the influence, he or she should hire a DUI defense attorney right away. In many DUI defense cases, part of the outcome of the case depends on the results of sobriety tests. Here is what drivers need to know:


The National Highway Traffic Safety Administration has standardized three different field sobriety tests. Officers can use these to try to determine whether or not a person has been driving under the influence, but it is important for drivers to remember that they do not have to submit to them. The validity of these tests and how officers use them is often a major issue during trial. Not doing these tests does not make you guilty of a DUI.

  • The Horizontal Gaze Test: This field sobriety test is also referred to as the horizontal gaze nystagmus test. This involves the officer moving an object horizontally in front of the driver’s eyes. When the eyes move side-to-side, there is a natural and involuntary jerking of the eyes, which can increase dramatically if a person is intoxicated.
  • The Walk and Turn Test: The standard walk and turn test is exactly what it sounds like: the driver is asked to walk a number of steps (nine) placing heel to toe each time, turning on one foot, and returning in the other direction. Law enforcement officials look for loss of balance during the walk or the turn, using arms for balance, incorrect number of steps, or space between the feet when walking.
  • The Standing on One Leg Test: This test requires the driver to lift one of his or her legs about six inches from the ground and count aloud for about 30 seconds. The law enforcement official looks for cues like imbalance, hopping to keep balance, using arms to keep balance, and putting the foot down.
  • Time Estimate Test: The officer will ask a driver to count silently and estimate 30 seconds. They will instruct a person to tell the officer when they think 30 seconds has passed. Law enforcement experts will allege that an estimate that is significantly off is a sign that someone is impaired due to drugs or alcohol.


There are three main chemical tests that officers may use to gauge a driver’s BAC. A driver does not have to submit to these tests either, but in many states this can result in license suspension.

  • Breathalyzer: A breathalyzer test measures BAC through a person’s breath. The driver blows into the device for a length of time and it estimates the blood alcohol concentration from deep lung tissue. The small handheld devices used by officers in the field can be very inaccurate and often have not been properly calibrated.
  • Blood: A blood test is usually performed by a license phlebotomist and can in some cases be challenged in a DUI trial. A defense lawyer can file a motion to have this sample split and re-tested if there is concern that the analyzer used by law enforcement wasn’t working properly.
  • Urine: Urine tests are not generally used anymore and a driver cannot typically opt for one in California. The only cases in which a urine test might be used is if an officer cannot get access to a blood or breath test.