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Field Sobriety Tests

Field sobriety tests (FSTs) are a series of tests that are intended to measure a person's balance, coordination, cognitive function and ability to follow directions. When a San Francisco Police Officer, California Highway Patrol Officer, San Francisco Sheriff's Deputy or other law enforcement officer stops someone for suspicion of driving under the influence, the person may be asked to perform a series of Field Sobriety Tests. A driver is not required to perform Field Sobriety Tests in California. If a driver chooses to perform the tests, the officer will closely monitor and record the person's balance, coordination, and ability to follow directions.

Field sobriety tests can be divided into two types. The first type of field sobriety tests are Standardized Field Sobriety Tests (SFT's). The second type of field sobriety tests are either called Non-Standardized Field Sobriety Tests or merely Field Sobriety Tests.

If a driver chooses to perform the field sobriety tests, they will first be asked to step outside of their car. The driver will then be asked to complete certain tasks such as touching their finger to their nose, walking and turning, and following a pen from side to side with their eyes. The officer will observe the person as they perform the field sobriety tests and take note of the person's performance on each test.

It is important to note that some people have difficulty performing Field Sobriety Tests. This may be for any one of several reasons, including poor instructions, fatigue, lighting, weather conditions, nervousness, physical condition. Each test's degree of difficulty may also impact a person's ability perform. Scientific studies sponsored by the Federal Government have shown that most field sobriety tests are unreliable, which has led some law enforcement agencies to adopt a set of three Standardized Field Sobriety Tests which include Horizontal Gaze Nystagmus (HGN), One Leg Stand, and Walk and Turn test.

Horizontal Gaze Nystagmus (HGN) Test

The Horizontal Gaze Nystagmus test, also known as HGN test, is not a test, but actually an eye examination. The officer will hold a stimulus, such as a pen or finger, about 12 to 15 inches from the driver's face. The officer will tell the driver to keep their head still and follow the stimulus with their eyes. The officer will then move the object from side-to-side while watching the driver's eyes. If the driver's eyes fail to smoothly track the stimulus, involuntarily jerk or tremble at the extreme outer edge of vision, and display an onset of nystagmus prior to forty-five (45) degrees, it can be interpreted as a sign that the person is impaired by alcohol.

One Leg Stand Test

During the one leg test, the person will be asked to stand with their heels together and their arms at their side. The officer will then ask the person to raise one leg six inches off of the ground and to count out loud until told to stop. The officer will watch to see if the person raises their arms, loses balance, sways, or puts their foot down.

Walk and Turn Test

During the walk and turn test, the officer asks the person to take nine heel-to-toe steps, stop, turn, and take nine more heel-to-toe steps. While the person performs the test, the officer will look to see if he or she can follow instructions, maintain balance, touch heel to toe and stay on a designated line.

San Francisco DUI Attorney

If you have been arrested for DUI in San Francisco, being represented by a qualified attorney is critical. A qualified DUI attorney will protect your rights, inform you of your legal options, investigate the circumstances of your arrest, and may question law enforcement officers and other witnesses. Additionally, a skilled DUI attorney will provide the resources and aggressive defense to successfully fight your DUI charges or minimize the impact of a DUI conviction.

DUI lawyer Robert Tayac has been helping people charged with DUI in San Francisco for more than twenty years. He has the education, specialized training, and experience to effectively handle your drunk driving case. Mr. Tayac can also schedule your DMV Hearing and represent you at the Hearing in the DMV Case. Remember, a driver suspected of DUI has only 10 days from the date of the DUI arrest to prevent the automatic suspension of their driving privilege.

Contact The Office

Mr. Tayac and the DUI investigators and experts working with him stand ready to help you or your family member. A member of the office is available to speak with you regarding the case any day of the week between the hours of 8:00 a.m. and 8:00 p.m. Pacific Standard Time at 415-552-6000.

When you hire Robert Tayac, you will know that you have hired a knowledgeable and trustworthy DUI defense lawyer.

If you hire the Law Office of Robert Tayac, you will know that you have retained the services of the most knowledgeable and experienced DUI defense team.

Why Choose Our Firm?

Attorney Robert Tayac Puts a Long, Decorated Career to Work for You
  • Puts Over 20 Years of Experience Toward Your Case

  • Specialized Education in DUI Defense

  • Has Trained Other Attorneys in San Francisco

  • Former San Francisco Police Officer & Police Inspector

  • Certified by the SFPD on the Intoxilyzer 5000 Testing Device

  • Co-Authored the 4th Edition of California Drunk Driving Defense

  • Boasts a Successful Record Achieving the Best Result for His Clients

  • Takes the Time to Understand You & Your Case

Client Testimonials

  • “...you achieved for me an outcome exceeding what is typical for Santa Clara County.”


  • “Thank you again Robert, and we are just hoping that we can move on and 'let it go'.”


  • “Very professional and has a great human element that many lawyers don't have.”

    Former Client

  • “I got my life back on track because Robert understands people, and he is genuinely concerned for his clients.”


  • “...thank you for walking me through this process and making me feel at ease.”


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