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DUI Investigations

Field sobriety tests (FSTs) are a series of tests that measure a person’s agility, attention, coordination, and balance. When a person is stopped by an officer for driving under the influence, the person may be asked to perform a series of field sobriety tests. While the person performs the test, the officer will closely monitor the person’s balance, coordination, and ability to follow directions. Field sobriety tests are voluntary, which means a person has the right to refuse to perform them.

It is important to know that even a sober person could have difficulty passing the field sobriety tests. There are many reasons a person could possibly fail the tests such as poor instructions, fatigue, weather conditions, or nervousness. Each tests’ degree of difficulty could also impact a person’s ability to pass or fail.

Scientific studies have shown that most field sobriety tests are unreliable, which has lead some states to adopt a set of 3 standardized tests which include the walk and turn test, the one leg stand test, and the nystagmus test.

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 the person can follow instructions, maintain balance, and stay on the designated line.

One Leg Stand Test

During the one leg stand 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 (their choi ce) six inches off of the ground while counting out loud until told to stop. The officer will watch to see if the person loses balance, sways, or puts their foot down.

Nystagmus Test

During the horizontal gaze nystagmus test, also known as the horizontal or vertical gaze test, the officer will hold an object such as a pen about 12 to 15 inches from the person’s face. The officer will then move the object from side-to-side while watching the person’s eyes. If the person’s eyes involuntarily jerk or tremble, it can be taken as a sign that the person has consumed alcohol.

Why Field Sobriety Tests Are Not Always Accurate

If an officer does not give specific instructions, failure on these tests is inevitable. The suspect loses points on the tests if he/she raise their arms, sways, loses balance, or does not follow directions. If it is dark outside, the person may have a hard time coordinating his/her movements, which can lead to hopping or swaying while trying to stay balanced.

Slippery roads or adverse weather conditions can also complicate tests. If a person is nervous or unsure of the officer’s directions, he/she could make mistakes that will make them appear to be under the influence according to the tests’ standards.

Why Blood Alcohol Testing Is Not Always Accurate

It is important to remember that the blood alcohol test is supposed to determine the blood alcohol concentration during the time the driver was operating his/her motor vehicle, not after the fact. This means there can be a significant difference between a driver’s BAC at the time of driving and the driver’s BAC at the time the test is taken.

There are three types of tests law enforcement uses to determine a person’s blood alcohol level. Blood alcohol can be measured by a person’s breath, blood, or urine. Certain factors such as gender, amount of alcohol consumed, weight, type of alcohol consumed, and food consumption can make blood alcohol test results much higher.

San Francisco DUI Attorney

If you have been arrested for DUI in San Francisco, obtaining a qualified attorney is the most important decision you can make. A DUI attorney can protect your rights, inform you of your legal options, investigate the conditions of your arrest, and question law enforcement and witnesses. A skilled attorney can also provide the resources and aggressive defense you will need to successfully fight your DUI charges.

The Law Office of Robert Tayac has been helping people charged with DUI in San Francisco for over two decades. Attorney Robert Tayac has the education, training and experience to defend your drunk driving case. Attorney Tayac can also help you schedule your hearing with the DMV and represent you at the hearing. Remember, you only have 10 days to prevent your license from being suspended. When you work with Robert Tayac, you can be assured that you are retaining the services of a knowledgeable, trustworthy DUI defense lawyer.

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.

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

  • “I will always be eternally grateful for your help and extreme kindness.”

    T., Captain of Police

  • “I just wanted to thank you for your wonderful work on getting my conviction expunged from my record.”

    N.D., DUI Attorney

  • “His in depth knowledge and expertise within his field, along with deep and lasting relationships with the District Attorneys office and everyone involved are without a doubt unmatched.”


  • “I am very happy with his professional expertise that he provided during this stressful time.”


  • “I can’t imagine things going any less painlessly than you made it for me.”


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