August 27, 1998 98-R-0958




FROM: Christopher Reinhart, Research Attorney

RE: Field Sobriety Tests For Driving While Impaired By Drugs

You asked whether field sobriety tests relate to a driver’s impairment by drugs as well as alcohol and whether there is a difference in the statutes or cases in determining probable cause to make an arrest for driving under the influence of drugs instead of alcohol.


The same field sobriety tests (FSTs) are used in Connecticut to gauge alcohol or drug impairment. The statutes and case law do not distinguish between their use to determine probable cause for alcohol or drug impairment and we are not aware of any cases that have even raised this issue. In impaired driving cases, probable cause to make an arrest is generally based on observing the vehicle in motion, questioning and observing the driver, and the results of the field sobriety tests. But whether an officer suspects alcohol or drug impairment may affect whether a suspect is given a blood, breath, or urine test after his arrest.

Although we did not find any case law, there may be some basis for a distinction between FSTs used to detect alcohol and drugs. The Los Angeles Police Department (LAPD) and the National Highway Traffic Safety Administration (NHTSA) have developed specific procedures for testing drug impairment. Defense attorneys also point out flaws in the use of FSTs in general and point out specific difficulties with drug detection that could affect a finding of probable cause for driving under the influence of drugs. These problems include the objective factors involved in administering a test, the wide range of effects that different drugs can have on different people, and the lack of experience and training that officers may have with detecting drugs. Attached are some relevant portions of defense manuals dealing with cases of driving under the influence of drugs.


The development of specific programs for detecting drug impairment in some jurisdictions suggests that there may be a basis for distinguishing between field tests to determine impairment by drugs and alcohol. The Los Angeles Police Department (LAPD) has made a distinction between alcohol and drugs and specified a set of tests and procedures for detecting drug use based on research sponsored by the National Highway Traffic Safety Administration (NHTSA). The LAPD uses eight tests: one-leg stand, finger-to-nose, walk-the-line, standing steadiness, nystagmus (involuntary jerking as the eyes gaze to the side or upward), pupil reaction, pupil size, and pulse rate. The officer also looks for skin marks, apathy, drowsiness, and hyperactivity. The LAPD believes that an experienced officer should be able to determine the type or class of drugs involved (Taylor, Drunk Driving Defense § 1.4.1).

The NHTSA has also developed a specific program for drug detection, the Drug Evaluation and Classification program, based on a program developed by the LAPD. This program is not a field procedure but "a post-arrest investigative procedure that requires a carefully controlled environment that would be difficult if not impossible to secure at roadside" (NHTSA, U.S. Dept. of Transp., Drug Evaluation and Classification Program, Briefing Paper, (July 1990)). Richard Erwin, in Defense of Drunk Driving Cases, calls the NHTSA process for determining drug impairment "more complicated and [it] requires more equipment and training than that for alcoholic impairment. The two processes have some points in common, including a breath test for alcohol and administration of standardized field sobriety tests." (Erwin Defense of Drunk Driving Cases § 12.04) Under this program, Drug Recognition Experts (DREs) are trained and certified to determine whether a suspect arrested by an officer is under the influence of drugs. The DRE observes and questions the suspect and has the individual perform tests before a chemical analysis is ordered. Twenty-six states and the District of Columbia had adopted this program through April 1995 (Erwin).

Manuals for defense attorneys point out a number of means of attacking FSTs in general. Research from the NHTSA supports the accuracy of FSTs (M. Burns & E. Anderson, A Colorado Validation Study of the Standardized Field Sobriety Test Battery, NHTSA, No. 95-408-17-05 (1995)). But other research attacks their use at trial and as a basis for probable cause (Nowaczyk & Cole, Separating Myth from Fact: A Review of Research on Field Sobriety Tests, Champion (Aug. 1995)). According to Erwin, many subjective factors may be involved in giving the tests. The NHTSA has standardized procedures for insuring the accuracy of the tests but they are not always followed. Other factors include the physical conditions of the testing environment, the particular characteristics of the individual, and the pressures placed on the individual (Erwin).

These manuals also point out several additional problems specifically related to detecting drugs. Drug impairment is involved in fewer cases and officers have less training and less experience than with alcohol detection. Detection of drugs can be more difficult because the effects of different drugs can vary greatly depending on the type of drug and the individual. Also, alcohol can often be easily detected on the breath of a suspect but drugs generally do not have an odor, except for marijuana. In addition, some tests may be effective with certain drugs when others are not. For example, certain categories of drugs induce nystagmus while others do not (Erwin § 12.04[3]).