The National Highway Traffic and Safety Administration (NHTSA) developed a standardized battery of tests to help police determine whether probable cause exists to arrest a suspected drunk driver for DWI. Research for these tests began in 1975 when NHTSA funded research to develop a standardized battery of tests. Prior to the development of the SFSTs, officers around the country used a variety of techniques based mostly on personal observation to try and assess a driver’s potential impairment or intoxication.

Developing the SFSTs

These tests were unscientific, unevenly applied, and subjective. During this time, states had tremendous difficulty proving whether a driver was under the influence in court and officers had difficulty articulating their reasons for making arrests. Drunk driving accidents and fatalities in the country were also at an all-time high. Accordingly, the federal government got involved and sponsored several validation studies to determine which tests had the most so-called reliability. NHTSA backed studies examined:

  • The Horizontal Gaze Nystagmus (HGN) Test;
  • The Walk and Turn
  • The One Leg Stand Test
  • The Finger Count
  • The Finger to Nose Test
  • A pencil and paper tracing exercise

The first three: HGN, Walk and Turn, and One Leg Stand were deemed to be the most reliable of the tests. In 1983, NHTSA sponsored field test studies to put these three tests in action and assess how accurately they predicted an elevated blood alcohol content in a suspected drunk driver. According to NHTSA, these tests reliably predicted blood alcohol content above 0.10 83% of the time.

In 1995, NHTSA sponsored another study, often referred to as the Colorado study, that supposedly further validated the accuracy and reliability of these tests. In 1997, the so-called Florida Study supposedly validated the SFSTs for reliably predicting blood alcohol content abov 0.08 in response to most of the states lowering the legal limit from 0.10 to 0.08. The accuracy, reliability, and predictability of these studies and the science behind them have been widely criticized in the academic world. Nevertheless, they serve as the linchpin for DUI and DWI enforcement, investigation, and prosecution across the United States.


Over time, NHTSA developed curriculum and training to certify state and federal law enforcement officers in the administration and interpretation of these standardized field sobriety tests. Setting aside the questionable methods and results achieved by government funded studies to make the prosecution and conviction easier for state and local governments across the country, these tests are widely viewed within the criminal justice system as persuasive evidence of a suspected drunk driver’s impairment. NHTSA’s curriculum and training evolved into a certification program that many police officers attend and complete. In response, many criminal and DUI defense lawyers began studying and ultimately completing the same NHTSA training and certification that the DWI enforcement officers get. The training involves around 20 hours of coursework and classroom instruction followed by a test in which the student must accurately complete the SFSTs and pass a written test.

Attorney Morgan E. Leigh has completed this training and received the same certification that the alcohol enforcement officers themselves receive. Because while many DUI defense lawyers do not believe that the studies are scientifically accurate and reliable, its important to learn what the police officers themselves have learned to effectively cross-examine them at trial. In fact, when arrested for DUI and looking for a lawyer, one of the first questions to ask the lawyer is whether they have obtained this NHTSA certification. Many in the DUI defense community view this certification as the basic level of training and education to receive to effectively fight DUI and DWI cases.

Importantly, the NHTSA curriculum manuals reference that the officers must complete the administration of the tests in the standardize manner in which they are instructed. The manuals go on to further state that failure to administer the tests in the standardized manner can compromise the validity of the results. In other words, if the officers do not administer the tests correctly, then the results are not reliable.

NHTSA created the first manual in 1987 and has periodically updated it all the way through 2018. We have provided below downloadable versions of each manual including the manuals created for the instructors of the course. These tools are indispensable resources for any competent DUI and DWI defense lawyer.

Hiring a Lawyer

Getting arrested for DUI or DWI can have life-changing consequences for anyone who cares about their future. Hiring the right lawyer can make all the difference in the world on one’s case. Given how states, including Maryland, aggressively prosecute these types of cases, going at it alone or with a lawyer with little experience defending these types of cases can make a bad situation way worse. Attorney Leigh has experience fighting on behalf of clients arrested for DUI and DWI in Maryland. She is an aggressive advocate who will fight to protect your rights and your future. Contact her today for a full case evaluation.

Maryland Criminal Law Reference Materials