Field Sobriety Tests

Standardized Field Sobriety Test Podcast!

Standardized Field Sobriety Testing in Michigan and across the nation: Interview with Tony Corroto regarding new NHTSA 2013 SFST training guide

The new 2013 NHTSA student guide makes radical changes to the training of police officers in drunk driving detection and field sobriety testing.

Field sobriety tests are supposed to be able to determine whether a person is intoxicated. Police officers might request that a motorist recite a portion of the alphabet, count backwards, or engage in a variety of dexterity tasks, e.g. finger to nose, finger-count, pick a number, etc. The Standardized Field Sobriety Test battery (SFSTs) have studied and supposedly validated three specific tests described as the Horizontal Gaze Nystagmus test (HGN), the Walk and Turn test (WAT), and the One Leg Stand test (OLS). Without chemical test evidence, a prosecutor may submit evidence of a person's performance of these tasks to a jury in most jurisdictions as substantive evidence of impairment and intoxication.

Field sobriety tests blur the distinction between direct and circumstantial evidence. A motorist who cannot say his or her alphabet or walk heel-to-toe might be perceived as intoxicated, but it is reasonable to question this evidence. Judges describe the difference between direct and circumstantial evidence to jurors as follows: "Direct evidence is evidence about what we actually see or hear. For example, if you look outside and see rain falling, that is direct evidence that it is raining. Circumstantial evidence is evidence that normally or reasonably leads to other facts. So, for example, if you see a person come in from outside wearing a raincoat covered with small drops of water, that would be circumstantial evidence that it is raining." Although police officers and prosecutors will deny it, a person's inability to perform a heel-to-toe test is direct evidence that the person could not perform it, and nothing more. At best, the inability to perform the test provides only circumstantial evidence that the person might be intoxicated. Because field sobriety tests are not nearly as accurate or reliable as they purport to be, the evidence drawn from these tests may cross from permissible circumstantial evidence into the realm of impermissible speculative evidence.

Wrongful convictions of absolutely innocent people can result from reliance on the field sobriety tests. As an example, police and prosecutors claim that the HGN test is the most accurate test. A recent study produced by the federal government to support this claim released raw data that directly contravened the study's findings. The raw data conclusively proved that the most highly trained police officers working under laboratory conditions incorrectly identified 77% of alcohol-dosed subjects as being over .08 when they were under the legal limit. Nearly 40% of the false arrest decisions involved subjects under .05, even though these officers would have provided compelling testimony to jurors had this occurred roadside.

I am in the process of preparing a video-audio presentation in powerpoint format for potential clients, researchers, and the media that will replace this page in the near future.  For now, however, I have the following powerpoint presentation from earlier this summer.  These materials are not self-explanatory.  Frankly, the powerpoint will be a little sketchy to anyone that didn't attend the seminar, but I promised the lawyers at that seminar that I would provide a copy.  --William Maze


CDAM 2012 Introduction to Field Sobriety Tests (Powerpoint presentation presented by William Maze to criminal defense lawyers at the CDAM summer conference)

Materials referenced in the seminar:

1995 Colorado Field Sobriety Testing Study

1997 Florida Validation Study

San Diego Study



Here is a presentation from Sgt. Perry Curtis and Ken Stecker. Sgt. Curtis is in charge of the breath testing program at the Michigan State Police, and Mr. Stecker is a prosecuting attorney. A few years ago, I filed a lawsuit against the Michigan State Police pointing out the administrative rules and rule-making authority, claiming that the Datamaster handbook constituted procedures under the APA. The Michigan State Police denied this to high-heaven because it would have subjected them to attack. It appears that they have changed their tune, even though they were successful in convincing a Lansing judge that their procedural framework was all hunky dorey. The very arguments I raised in that lawsuit are detailed by Curtis and Stecker in this power point presentation. In any event, this power point presentation contains a lot of great materials for those that are unfamiliar with the Datamaster rules, procedures, and equipment. It is reproduced here without permission as a public record subject to FOIA: