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Law enforcement agencies around Philadelphia and the rest of the state aggressively enforce laws the prohibit driving under the influence of alcohol or drugs (DUI). In fact, according to the Pennsylvania Department of Transportation,[1] there were 52,636 people arrested on suspicion of DUI during 2014. When a driver is pulled over and a law enforcement officer suspects that he or she is drunk, the officer engages in an on-the-spot investigation to determine whether the driver is, in fact, under the influence of drugs or alcohol. Law enforcement has a variety of investigative techniques at their disposal, ranging from simple observations of a suspect’s appearance, behavior, and demeanor to the chemical analysis of a person’s blood, breath, or urine.

One of the more common ways that law enforcement gathers evidence to support the assertion that a driver is intoxicated is to request that he or she submit to the Standardized Field Sobriety Test,[2] or SFST. The SFST is actually a battery of three distinct tests that were developed by the National Highway Traffic Safety Administration (NHTSA) and the Southern California Research Institute. The three tests that comprise the SFST are detailed below.

  • The Horizontal Gaze Nystagmus (HGN) – Nystagmus is an involuntary twitching of the eye muscles that occurs when the eyes look to either direction at a significant angle. When a person is intoxicated by alcohol, this involuntary movement becomes more pronounces and occurs at lesser angles. To conduct this test, the test administrator asks that the subject track an object across his or her field of vision while the administrator observes for signs of alcohol intoxication. The three signs of impairment law enforcement looks for are the eyes not following an object smoothly, distinct jerking at maximum deviation, and whether the jerking starts when the angle of the eyes is within 45 degrees of center.
  • One-Leg Stand – The One-Leg Stand test requires that the subject stand with one foot raised approximately six inches from the ground while counting aloud by thousands for 30 seconds. The officer conducting the test looks for four indicators of impairment – swaying, using arms to maintain balance, hopping to maintain balance, putting the raised foot down on the ground.
  • Walk-and-Turn – In this test, the subject is asked to take 9 steps, heel-to-toe, along a straight line and then turn and come back in the same manner. The officer administering the test observes the suspect looking for the following 8 indicators of intoxication: balance while listening to instructions, starting the test before the instructions are finished, stopping to regain balance, not touching heel-to-toe, stepping off the line, using arms to maintain balance, making an improper turn, or taking the wrong number of steps.

The SFST is a tool to obtain evidence indicating that you are drunk

While the SFST is purportedly used to determine whether a person is drunk, in practice most law enforcement officers have likely already made a determination as to whether or not he or she has probable cause to arrest a person that they ask to perform the SFST. What this means is that the reason people are generally asked to perform the SFST is to allow the officer administering the test to obtain evidence to support his or he assertion that the driver is intoxicated. As a result, the SFST is not a test you can “pass” – if you have been asked to perform it, chances are that an officer strongly suspects that you are intoxicated. The best thing to do if you are pulled over and have been drinking is to tell the officer that you would like to speak to your attorney and call your lawyer as soon as you can.

Contact a Philadelphia criminal defense attorney today to schedule a case evaluation

Driving under the influence of alcohol or drugs is a serious criminal offense in the state of Pennsylvania and can result in significant legal penalties. In addition, the collateral consequences of a DUI conviction can affect a person for years, and can have a tremendous impact on nearly every aspect of your life. In some cases, a DUI may have an impact on your ability to get or keep a particular job or hurt your chances of being admitted into certain academic programs. As a result, it is highly advisable for anyone facing allegations of drunk driving or any other criminal offense to retain legal counsel as soon as possible. To schedule a consultation with Philadelphia criminal defense lawyer Brian Zeiger, please call our office today at 215-546-0340. 



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.