Standardized Field Sobriety Test

If you are a driver and have casually read or discuss drunk driving in the United States, chances are that you have heard of the Standardized Field Sobriety Test, 1 or SFST. This National Highway Traffic Safety Administration (NHTSA)-approved test was designed to help law enforcement have a standardized way to determine whether they have probable cause to arrest a driver for drunk driving.

If you have ever seen a dashboard camera video of a police officer requesting that a person walk a straight line or a follow a pen with his or her eyes, you have seen part of the SFST. While knowledge of the existence of the SFST may be common knowledge, it is not widely understood. Below are four things you should know about the SFST as a driver.

You Cannot “Pass” the Standardized Field Sobriety Test

Many drivers who are asked to perform the SFST are under the mistaken impression that if they just perform well enough, the officer that pulled them over will decide that he or she is sober and not arrest them. This is almost invariably false. First of all, the standardized field sobriety test was never designed to measure impairment, but rather to provide the test administrator with a probability that the test-taker has a blood alcohol content (BAC) over the legal limit of 0.08. As a result, it is simply an investigative tool, not a tool to determine whether a driver is drunk. If you have been asked to perform the SFST, the officer is in all likelihood simply gathering evidence is support of his or her assertion that you are intoxicated, rather than trying to determine whether you are intoxicated.

The Field Sobriety Test Actually Consists of Three Separate Tests

While it is often referred to as a singular “test,” the SFST actually consists of three distinct tests, which are described below.

  1. The Horizontal Gaze Nystagmus (HGN) – When the eyes are rotated to extreme angles, there is an involuntary jerking known as “nystagmus.” When a person is under the influence of alcohol, this jerking becomes more pronounced. The HGN test involves requesting that the driver follow a pen or other object from side to side across his or her field of vision while the officer observes at what point nystagmus begins. If it starts earlier than would be normally expected, it is considered a sign of intoxication.
  2. The Walk-and-Turn – The walk-and-turn test involves the officer asking the driver to take nine steps, heel-to-toe, along a straight line, and then turn around and return in the same manner. The law enforcement officer administering the test observes the test-taker for signs of intoxication both when the instructions are being given and when the steps are being taken.
  3. The One Leg Stand – Similarly to the Walk-and-Turn, this test allows the officer to evaluate the test-taker while the instructions are being given and while the subject is performing the requested action. In this test, the officer asks the driver to stand on one leg while counting out loud by thousands.

You can Refuse to Take the Field Sobriety Test

There is significant confusion regarding this aspect of the SFST, as many drivers are aware of the fact that there are legal consequences for refusing “testing” if they suspected of being drunk. In reality, Pennsylvania’s implied consent law, which states that drivers have impliedly consented to certain forms of testing, only applies to the chemical testing of your blood, breath, or urine. For example, if you refuse a breathalyzer and the officer has probable cause to believe you were drunk, your license may be administratively suspended. The implied consent law does not apply to the standardized field sobriety test, however, so there are no penalties associated with refusing it.

Call a Philadelphia DUI Defense Attorney Today to Retain Legal Representation

If you have been arrested for drunk or drugged driving in the Philadelphia area, you should Philadelphia criminal defense attorney Brian Zeiger immediately. A Pennsylvania DUI conviction can have a significant impact on your life and can hold you back for years. In addition to having the potential to result in fines, probation, the installation of an ignition interlock device, and even jail time, a DUI conviction could keep you from getting a job or being admitted to an academic program. To schedule a free case evaluation with Mr. Zeiger, call our office today at 215-546-0340 or send us an email through our online contact form.


Brian J. Zeiger, Esquire, is an experienced and successful criminal defense and civil rights attorney. He is a seasoned trial lawyer with significant experience before juries and judges. Brian understands civil rights cases, including Taser, Wrongful Death, Excessive Force, Police Brutality, Police Misconduct, Malicious Prosecution, Monell Claims, Sexual Assault, Prisoner’s Rights, Time Credit, Medical Malpractice, and Medical Indifference.