Do I Have to do the Field Sobriety Tests When Stopped for DUI?

Posted by Phillip Crawford | May 12, 2020

Field Sobriety Tests Are Not Mandatory

If you are stopped by the police and suspected of driving under the influence, the police will probably ask you to perform roadside tests known as Field Sobriety Tests (FSTs).  The police will frequently use your performance on the FSTs to justify arresting you.  If you go to trial, the prosecutor will use your performance on the FSTs to try to convince a jury that you were too impaired to drive safely.  Most people do not realize that they are not required to do these tests. There are good reasons why you should not do these tests.

In California, if you are lawfully arrested for driving under the influence of alcohol and/or drugs, you are then required to submit to a breath or blood test (aka a “chemical test”). If you are arrested for DUI and then refuse to submit to a chemical test, you can lose your driving privileges for at least one year, even if you are found not guilty of DUI. This is because California has an “implied consent” law (Vehicle Code Section 23612). This statute says that by driving a vehicle in California, you are consenting to having your breath or blood tested upon being arrested for a DUI.

There is no such “implied consent” law for FSTs.  Unless you are on probation for a prior DUI, there is absolutely no legal requirement to perform the FS's. So, why do so many people perform FSTs? Primarily, most people are not aware of their right to refuse FSTs. The police usually do not tell people that these tests are voluntary. Most people believe that they are being ordered by police to do FSTs. Understandably, most people believe that if a police officer asks you to step out of your car and do the FSTs, “to make sure you are ok to drive,” that this is an order that they have to follow. This is not true.

Some people choose to do FSTs because they think that they can prove they are not driving under the influence. These people think that they will pass the FSTs with flying colors and will be free to leave. However, even if you think that you are not impaired by alcohol or drugs, you should strongly consider refusing to perform FSTs.

The FSTs have very little scientific value.  There are three “standardized” field sobriety tests.  “Standardized” means they are always administered the same way by every cop.  They are: (1) the Horizontal Gaze Nystagmus test (in which you follow the cop's finger with your eyes); (2) the One Leg Stand test; and (3) the Walk and Turn test.  According to research done by the National Highway Traffic Safety Administration, these standardized tests to not measure a person's ability to drive safely.  If administered properly by trained police officers, they simply indicate that you drank alcohol.

Police officers frequently administer other FSTs which have not been standardized.  These FSTs have even less value.  But the government will still argue that your performance on these tests proves you were under the influence.

Further, very few people will perform these tests perfectly. At least 25% of sober people will fail some of these tests.  People who are overweight, over 65 years old, have knee or back problems, or are simply tired have problems doing FSTs. Just the stress of being stopped and questioned by the police can be enough to cause problems with your performance.

Moreover, these FSTs are rarely given in an ideal setting. Usually, these FSTs are performed on the side of the road with lots of noise and traffic nearby. The tests are also often performed on uneven surfaces. Also, police frequently give the instructions improperly.  Police often fail to follow their own training when demonstrating and evaluating test results. In one study, police watched sober people perform FSTs and the police determined that almost half of them were too drunk to drive.  In short, these tests are usually designed to result in failure.  (click here to read the study)

 Lastly, you should consider refusing to do FSTs for the simple reason that police officers frequently fail to record the results of the FSTs accurately. Police officers typically write their reports several hours after a person has been arrested and will frequently exaggerate any problems with your performance.   Sometimes we can review your performance on the police video recording.  It is incredibly common for the police report to be very different from the video footage.  But the FSTs aren't always captured on video. 

If you were arrested for DUI and you did FSTs, you should consult with a DUI attorney to discuss available defenses. An experienced DUI attorney can review all the evidence (including the police report and any audio/video footage of your arrest) and determine what defenses to argue. We know a lot about FSTs, including the many mistakes frequently made by law enforcement while administering the tests. Before you decide to just “plead guilty and get it over with,” call us for a free consultation.

About the Author

Phillip Crawford

Phillip Crawford is an award-winning DUI attorney. In 2018, he won the California DUI Lawyer's Association's top honor when he received the President's Award for excellence in DUI defense. His sole focus is defending DUI cases. Phillip is regarded by judges, prosecutors and fellow defense attorneys as the top DUI in the area who fights passionately for his clients.

Top-Rated, Award-Winning Criminal Defense Attorneys


The Crawford Law Firm has been committed to its clients for over fourteen years. Our focus is DUI and criminal cases in Monterey, Santa Cruz, San Luis Obispo, and Santa Barbara counties.

Free consultations are by appointment and we here to ease your mind and fight for you. Contact us today to schedule an appointment.