The following provides a basic overview of the field testing. Generally there are three “tests” administered on scene. These tests consist of the walk and turn, the one leg stand, and the horizontal gaze nystagmus. The three tests most often go together. They have shown 93% accuracy in Colorado in 1995, 95% accuracy in Florida in 1997 and 91% accuracy in San Diego in 1998. But, many scientists refute the validity of these tests.

The horizontal gaze nystagmus is still the most accurate of the three. This test can “provide valid indications to support arrest decisions at 0.08 and strongly suggests that it can provide valid indication of 0.04 and above”. When the horizontal gaze combines with the walk and turn, some say it has 80% accuracy. But, when tested with all three, a higher degree of accuracy exists. These three tests, however, have never been subject to peer review. Peer review is the process in which scientists publish their methods and results to other persons in their field. This allows for critical analysis of the data and results.

Taking Field Tests

Field testing will most often occur on the side of the road. Field testing happens after one gets suspected of being under the influence. The results of the test will help the officer to support evidence if they find you under the influence of drugs or alcohol. Understand that you do not have to take field tests.

You can simply tell the officer that you do not wish to take the tests. Remember to be polite with the officer because it can only help you later. Still, refraining from field tests is your right. You don’t have to take them and in most cases will only hinder you when it comes time for court. Conditions for field testing are often not ideal in some conditions. These conditions include uneven ground, poor lighting, weather and inappropriate clothing.

Standardized Field Sobriety Tests

Standardized Field Sobriety Tests (SFST) are psychophysical tests. A test consists of an “objective” and “standardized” measure of a sample of behavior, focusing on three elements:

1) Objectivity. Aspects of a test have basis in objective criteria, such as the scoring or the interpretation of the score, and not influenced by the subjective opinion of examiner.

2) Standardization. There is uniformity of procedure in the administration, scoring and interpretation of the test and results.

3) Behavior Sample. A representative sample of a person’s behavior from which one can draw inferences and hypotheses.

Psychological Tests

A test is not a psychological x-ray, nor does it necessarily reveal hidden conflicts and forbidden wishes.

Psychological tests must meet three criteria. These criteria are (1) Reliability, (2) Standardization, and (3) Validity. Many professionals use these tests. These professionals include psychologists, special education teachers, guidance counselors, psychiatrists, speech therapists, nurses and engineers.

Psychophysical tests should require evaluation of many factors. These factors include the subject’s appearance and condition, ability to follow instructions, as well as balance and coordination. These types of tests go by the name divided attention tests. This is because they require the subject to concentrate on more than one thing at a time. This divides the subject’s attention between mental and physical tasks. Studies have shown that a person who is under the influence of an alcoholic beverage may be able to perform one of these tasks but rarely both. If under the influence of an alcoholic beverage, people are likely to make certain predictable errors while attempting these tasks.

Since the mid 1970s, the National Highway Traffic Safety Administration (NHTSA), with the cooperation and assistance of the law enforcement community, has conducted research that resulted in the development of a battery of three standardized field sobriety tests. These tests are the horizontal gaze nystagmus, walk and turn and the one leg stand. They assist police officers in detecting impaired drivers.

Field Test History

The program, previously termed the improved sobriety testing, got validated in laboratory and field studies conducted by the Southern California Research Institute. The Los Angeles Police Department developed these tests. The methodology of conducting these tests is included in the NHTSA course “DWI Detection and Standardized Field Sobriety Testing”.

In 1986, the Advisory Committee on Highway Safety of the International Association of Chiefs of Police (IACP) passed a resolution. This resolution recommended that law enforcement agencies adopt and implement the field sobriety testing program developed by NHTSA. As the program grew, to ensure continued success, it needed nationally accepted standards. Standardization that established criteria for the selection and training of SFST practitioners would help ensure the continued high level of success of the SFST program. In 1992, the IACP Highway Safety Committee recommended the development of this system of nationally accepted standards.

In April of 1992, the IACP and NHTSA sponsored a meeting at the headquarters of IACP in Arlington, Virginia. Persons invited to this meeting included SFST instructors from several states, curriculum specialists and training administrators. The participants met in working groups. Their purpose was to reach a consensus concerning the many issues relating to the SFST program. They were also supposed to develop recommended minimum standards to the IACP Advisory Committee on Highway Safety. The standards were drafted and presented to the committee for their review at the midyear meeting in June 1992.

National Adoption

The Advisory Committee on Highway Safety by resolution adopted the National Standards for the SFST Program. Voting membership of the IACP subsequently approved the standards. To maintain the credibility and integrity of the program, agencies that use a training program other than one approved by the IACP must have the alternative curriculum approved. It has to get approved by the IACP Advisory Committee on Highway Safety as meeting the required learning objectives. This is supported by the National Highway Traffic Safety Administration.

Field Test Training

Presently, SFST Training for police officers (and the few DUI defense attorneys, including Attorney Ruane, who learned the regimen) must last for 16 hours. They must include at least two controlled drinking sessions utilizing volunteer drinkers. This is in accordance with section 1.2 of the standards for training in Standardized Field Sobriety Testing. In section 1.4, in order to satisfactorily complete the classroom portion of the training, SFST candidates must complete the IACP approved final examination. They must get a score of not less than eighty percent.

Candidates scoring less than 80% on the final can re-test one time under the supervision of a SFST instructor. The retest must happen not less than 15 days and not more than 30 days following the completion of the classroom training. The examination used shall not get administered to the candidate previously. If the candidate does not achieve a passing score on reexamination, the candidate must retake the classroom portion of the training. The candidate also has to pass the final examination.


The US DOT requires 35 practice tests within a six-month period. But, local and state police have varying requirements based on their own department’s criteria. A refusal of a chemical test doesn’t constitute a practice test. A blood alcohol reading must corroborate the evaluation of the suspect. The officer gets trained to conduct the HGN test last during their practice test period. The officer should not formulate an opinion based on the results or use it for probable cause to arrest. They are told not to document the test due to this.

At no time may a person that is tested be used more than once on a practice test. As a result of this it is necessary to review the documentation of the practice tests. This helps determine if the practitioner was properly recommended for certification.

Administering the Tests

After probable cause is determined, an officer will most often attempt to recover more evidence that the driver is under the influence of drugs or alcohol. An officer may ask a person to perform Standardized Field Sobriety Tests. In every state you do not have to take field sobriety tests. But, in each state the law is different regarding whether or not you have to consent to a blood breath or urine test. 

Standardized Field Sobriety Tests, usually conducted on the side of the road, do nothing to prove your sobriety. Oftentimes they can hurt your defense. The officer cannot force you to do these tests, so politely decline. However, in Connecticut, while you do not have to take a blood, breath or urine test, a refusal will trigger a longer DMV administrative suspension. If an officer tells you he will let you go if you take them, you should still decline. They can only add to the probable cause for your arrest.