"Drugged Driving" Defense and Prosecution: DRE Explained


Separate from the "per se" prong, RCW 46.61.502 also criminalizes driving while under the influence of intoxicating liquor or any drug, or under the combined influence of alcohol and a drug. [1]. Although Washington law has criminalized driving under the influence of drugs for many years,[2] law enforcement, perceiving problems proving that an individual was (1) under the influence of a drug and (2) that the drug impaired the ability to drive, developed the Drug Evaluation and Classification Program (DECP). The program was instituted in the 1970's at the Los Angeles police department in response to DUI stops with drivers who were "clearly impaired" but whose blood alcohol concentrations were low or zero.[3] Several government funded "validation studies" were performed which purported to show that a properly trained Drug Recognition Expert (DRE) officer accurately detects drug impairment and additionally will, in a percentage of cases, correctly predict the drug that caused the impairment.[4] Since 1989 the DRE program is administered pursuant to national standards promulgated by the International Association of Chiefs of Police (IACP).[5] The Washington State DRE program became operational in 1997. [6]



The DRE training manual defines a drug as: "...any substance, which, when taken into the human body, can impair the ability of the person to operate a vehicle safely." [7] This definition is at odds with the medical definition of drugs, since, for instance, the DRE definition of drugs excludes aspirin and includes airplane glue.[8]

For purposes of the training of a drug recognition expert, there are seven broad categories of drugs. The premise of the drug recognition training is that "Each category produces a different set of effects on the human mind and body. Each category exhibits different signs of drug influence, signs which come to light in the Drug Evaluation and Classification examinations." [9] The categories differ from one another in terms of how they impair driving ability and in terms of what impairment they cause.[10]

For DRE purposes, drugs are categorized as follows [11]:

1. Central Nervous System (CNS) Depressants.

These slow down the operation of the central nervous system. Alcohol is the best known CNS depressant and is "the model" in that other CNS depressants generally affect people in the same way as alcohol.[12] Other than alcohol, there are six major categories of CNS depressants: Barbituates, Non-Barbituates, Anti-Anxiety Tranquilizers, Anti-Depressants, Anti Psychotic Tranquilizers, and Combinations. Examples include Seconal, Soma, Xanax, Valium, Prozac (non-therapeutic doses,) Thorazine and Librax.[13] Generally speaking, a person under the influence of CNS depressants will “look and act drunk.”[14]

2. Central Nervous System Stimulants

These “speed up” the operation of the central nervous system, resulting in increased heartbeat, pulse, respiration, blood pressure and temperature and producing nervousness, irritability and an inability to concentrate or think clearly.[15] There are three major categories: Cocaine, Amphetamines (including Methamphetamine), and others. The latter category includes Ritalin, Ephedrine and Caffeine.[16]

3. Hallucinogens

These may create hallucinations or very distorted perceptions as a result of the nervous system sending strange or false signals to the brain. [17]Examples include LSD, Psilocybin, Peyote, and MDMA, otherwise known as Ecstasy.[18]

4. Dissociative Anesthetics

[19]This category consists of PCP and its various analogs along with other drugs that inhibit pain by cutting off or “disassociating” the brain’s perception of pain. Included in this category is Dextromethorphan, or DXM. Thought, reaction time and verbal responses are slowed but heart rate increases, along with distortion of signals received by the brain. This category thus shares some of the attributes of CNS Depressants, CNS Stimulants, and Hallucinogens. [20]

5. Narcotic Analgesics

There are two subcategories: Opiates - natural or derivatives of Opium, and Synthetics, produced chemically but with similar effects. “Analgesic” means pain-killer and all of the drugs in this category reduce reaction to pain. This is in contrast to an anesthetic, which stops nerve transmission of pain.[21] Examples within this category are Opium, Heroin, Codeine, Morphine, Hydrocodone, Oxycodone, Methadone, Demerol, Percodan, and Oxycontin.[22]

6. Inhalants

These are breathable chemicals that produce mind altering results. Three subcategories exist: Volatile Solvents (gasoline, glue, paint remover etc.), Aerosols (propellant gas in spray cans such as hair spray, insecticides, etc.), and Anesthetic Gases (nitrous oxide, amyl nitrite, butyl nitrite etc.) Effects differ by subcategory and can be similar to CNS Depressants, Stimulants, or Hallucinogens.[23]

7. Cannabis

This category includes the various forms and products of cannabis plants, such as marijuana, hashish, etc. Relaxation, euphoria, disorientation, altered time and distance perception and sedation are indicated effects.[24]B. DRE PROTOCOL (and comments):

A “twelve-step” protocol must be followed exactly for there to be a “valid” conclusion by the examining officer. The procedure is intended to determine:

(1) Whether the suspect is impaired; and if so,

(2) Whether the impairment relates to drugs or a medical condition; and if drugs,

(3) The category or combination of categories of drugs that is the likely cause of the impairment.[25]

The twelve steps of the examination are “standardized” in that the evaluation is to be administered the same way, every time.[26] The steps are:

1. Breath Alcohol Test:

This is administered to determine whether the concentration of alcohol is sufficient to be deemed the sole cause of impairment or whether it is likely that drugs are causing or contributing to impairment.[27] An accurate BAC is necessary.[28]

2. Interview of Arresting Officer: Where the arresting officer is not a DRE officer, this step is important since “...the arresting officers may have uncovered some drug paraphernalia or overheard the suspect using drug-related “street” terms, without recognizing their significance. A few minutes spent in a careful discussion with the arresting officer can alert the drug recognition expert to the most promising areas of investigation to be explored with the suspect.”[29] The specific areas of discussion with the arresting officer include: (a) the suspect’s behavior and attitude/demeanor: (b) suspect’s statements, especially regarding the use of “street terms” associated with drug paraphernalia, speech patterns, and whether the suspect complained of illness or injury, and (c) the physical evidence observed/gathered by the arresting officer, since “seemingly innocuous of familiar items may be recognized by trained DREs as being associated with possible drug use.”[30]

3. Preliminary Examination and First Pulse: This is described as a structured series of questions of the suspect, specific observations and simple tests that provides the first opportunity to examine the suspect closely and directly. A major purpose is to “rule out” medical conditions such as diabetes or illness.[31] An initial check of the eyes is performed and the first pulse is taken.[32] The size of each pupil is checked using a “pupilometer” (a reference card held next to the suspect’s eyes) and the eyes are checked for Nystagmus.

”Nystagmus” is “the involuntary oscillation of the eyeballs, which results from the body’s attempt to maintain orientation and balance. Horizontal Gaze Nystagmus is the inability of the eyes to maintain visual fixation as they turn from side to side or move from center focus to the point of maximum deviation at the side. Vertical Gaze Nystagmus is an involuntary jerking of the eyes (up and down) which occurs when the eyes gaze upward at maximum elevation. [33]

4. Eye examinations: Three eye tests are administered: (1) Horizontal Gaze Nystagmus, (2) Vertical Gaze Nystagmus and (3) Lack of Convergence. Lack of Convergence is the “inability of both eyes to draw in toward the center (cross) while fixating on a stimulus being moved in toward the bridge of the nose.[34] The theory is that certain kinds of drugs induce nystagmus vertically or horizontally and others cause lack of convergence, which is the inability of the eyes to converge toward the bridge of the nose. Still other drugs cause different combinations of these three observations.

The DRE uses horizontal nystagmus “onset angle” and the equation [BA= 50- angle] to estimate the suspect’s blood alcohol level.[35] [Blood alcohol = 50- onset angle of HGN].[36] Thus if the angle of onset is 45 degrees, the estimated BAC is .05. This estimate is compared with the previously administered breath test result in order to “obtain a gross indication of the possible presence of another CNS Depressant, a Disassociative Anesthetic such as PCP, or an Inhalant.”[37]

5. Divided Attention Tests:

”Divided Attention” physical tests are given to determine whether impairment exists. These are (1) Romberg balance (2) Walk and turn (3) One Leg Stand and (4) Finger to nose. The Walk and Turn and One Leg Stand tests have “validated clues for impairment,”[38] whereas the Romberg and Finger to Nose tests have not been so validated.[39]

6. Vital signs and Second Pulse:

Here the DRE performs “systematic” checks of the suspect’s pulse rate, blood pressure and body temperature. Medical instruments are used including a stethoscope, a sphygmomanometer (blood pressure cuff) and a thermometer. Note that the pulse is also checked two other times during the entire DRE examination: during the Preliminary Examination and during the Examination for Muscle Tone. The theory is that certain categories of drugs elevate blood pressure, pulse rate and raise the body temperature. Changes in the opposite direction may indicate different drugs.[40] A chart shows the asserted relationship of each of these factors to impairment by a particular type of drug. Note that very general “averages” are given for these measurements as follows: “Normal” systolic blood pressure is 120-140; “Normal” diastolic blood pressure is 70-90; “Normal” pulse in an adult male is 60-90 and “Normal” temperature is 98.6 plus or minus 1 degree Fahrenheit.[41]

7. Dark room examinations and ingestion examination: Here the pupils are checked for reaction to light and for their size and the results recorded on a chart. Using a pupilometer (reference card held next to the eye) estimates of pupil size are made under varying lighting conditions: (1) room Light, (2) near total darkness, and (3) direct light.[42] Also the nose and mouth are checked for evidence of ingestion of drugs by nose or mouth. In the dark room session, the nasal area and oral cavity are examined and notes taken regarding observations.[43]

8. Examination for Muscle Tone:

Three degrees of muscle rigidity are measured on an arm:

flaccid, normal or rigid. The theory is that certain drugs cause muscles to be hypertense while others cause muscles to be loose and flaccid. The DRE is instructed to “firmly grasp the upper arm and slowly move down to determine muscle tone.[44]

9. Examination for Injection Sites and Third Pulse:

Here the DRE examines the suspect’s arms, hands, fingers and neck for tracks or needle marks. If any are found, they are noted in a box on the police report. At this time the third pulse is taken.

10. Interrogation, Statements and Other Observations:

By this time, the DRE should have reasonable grounds that the suspect is under the influence of drugs and “at least an articulable suspicion” as to the category or categories of drugs causing impairment.[45] Now DRE asks additional “probing questions” to confirm the suspicion concerning the drugs involved.

11. Opinion of Evaluator:

Here the DRE opines whether the suspect is under the influence of a drug or drugs and if so, the category or combination of categories of drugs that is the probable cause of the suspect’s impairment. The student manual devotes an entire chapter to the writing of this report. As that chapter observes:

”Successful prosecution of a DRE cases will depend, more than anything else, on the evidence that you supply, and on how clearly and convincingly you present that evidence...The chemical test simply cannot prove that the suspect was impaired, or under the influence at the time the violation occurred. It is up to you to prove that, and to prove that the nature of the impairment was consistent with some category or combination of drugs.”[46]12. Toxicological Examination:

A blood test is requested of the suspect and subsequently analyzed.

Defending a driver accused of “drugged driving” is uniquely challenging to the dui defense attorney. Without a doubt the defense attorney is at a distinct disadvantage unless he or she takes the time to know more about the “science” of drug recognition than is known by the police witnesses. The attorneys in our firm have defended DRE “drugged driving” cases in a variety of jurisdictions, from Seattle Municipal Court to King County District Court, Whatcom and Skagit Counties and other jurisdictions within Washington State.

This article has been condensed from seminar materials prepared by Seattle DUI attorney Jon Fox for his presentation at the 2006 seminar, “Defending DUIs” which was attended by over 300 attorneys. Footnote references are below.

[1] RCW 46.61.502 (1)(a) (1) A person is guilty of driving while under the influence of intoxicating liquor or any drug if the person drives a vehicle within this state:(a) And the person has, within two hours after driving, an alcohol concentration of 0.08 or higher as shown by analysis of the person’s breath or blood made under RCW 46.61.506; or(b) While the person is under the influence of or affected by intoxicating liquor or any drug; or(c) While the person is under the combined influence of or affected by intoxicating liquor and any drug.

[2] The Washington legislature criminalized driving under the influence of any drug beginning in 1975. Laws of 1975, 1st Ex.Sess., ch. 287, sec. 1. Prior to that, Washington statutes continually criminalized driving under the influence of any narcotic drug beginning as early as 1927. Laws of 1969, ch. 1 sec. 3; Laws of 1965, Ex.Sess., ch. 155, sec. 60; Laws of 1961, ch. 12, sec. 46.56.010; Laws of 1927, ch. 309, sec. 51. (State v. Rios-Gonzales 130 Wn.App 1016 (2005)-unpublished opinion.)

[3] Drug Evaluation and Classification Training “Student Manual” HS 172 R4/93 P.III-1.

[4] See, e.g. Field Evaluation of the Los Angeles Police Department Drug Detection Procedure, DOT HS 807 012 (February 1986), also known as the “173 Case Study,” and the Arizona Drug Recognition Expert (DRE) Validation Study, Final Report to Governor’s Office of Highway Safety, Eugene Adler/Marcelline Burns (June 4, 1994.)

[5] International Standards of the Drug Evaluation and Classification Program, DEC Standards Revision Subcommittee of the Technical Advisory Panel, IACP, 1999, P. 3., State v. Baity, 140 Wn.2d 1, 4, (2000).

[6] State v. Baity, Supra, at 5.

[7] DRE “Pre-School” Instructor Manual, HS 172A R1/06, P.I-7.

[8]Drug Evaluation and Classification Training “The Drug Recognition School” Student Manual, HS 172 R4/93, P.II-2.

[9] Drug Evaluation and Classification Training, “The Drug Recognition School,” Student Manual, National Highway Traffic Safety Administration 1993 Edition HS 172 R4/93, page II-3..

[10] DRE “Pre-School” Instructor Manual, HS 172A R1/06, P.1-7.

[11] See Drugs and Human Performance Fact Sheets, DOT HS 809 725, NHTSA 2004 regarding the known effects of many drugs; also at www.nhtsa.dot.gov/people/injury/research/job185drugs/drugs_web.pdf.

[12] DRE Student Manual HS 172 R4/93 P IX-2.

[13] DRE Instructor Manual, Supra, HS 172 R1/06 at IX 2-10.

[14] Id., at IX-12.

[15] Id., at X-1 -X-2.

[16] Id., at X-2.

[17] DRE “Pre-School” Instructor Manual HS 172A R1/06 I-11.

[18] DRE School Instructor Manual HS 172 R1/-6 XIV-5.

[19] In all DRE manuals prior to the 2006 revision now in use in Washington State, this category is referred to as “Phencyclidine (PCP).” The change in name occurred in 2005 on the directive from the IACP DRE Technical Advisory Panel (TAP). DRE School Instructor Manual HS 172 R1/06 P.XVI-1.

[20] Id., at XVI-1.

[21] Id., at XVII 1-2

[22] Id., at 5-8.

[23] Id., at XIX -1.

[24] Id., XXI 5-6.

[25] DRE School Instructor Manual HS 172 R1/06 IV-1.

[26] A DRE may not offer an opinion regarding drug classification of a suspect unless all twelve steps of the protocol have been undertaken. State v. Baity, Id., at 18; See State v. Aman, 95 P.3d 244, 248 (Ore. App., 2004), absence of toxicological test results (12th step of DRE examination) precludes admission of DRE conclusions.


[28] DRE School Instructor Manual HS 172 R1/06 IV-4-5.

[29] DRE Student Manual, HS 172 R4/93 at IV-3.

[30] DRE Student Manual, HS 172 R4/93 supra, at IV-7.

[31] Note that this step follows the interview of the “arresting officer.” As the defendant is under arrest at this point, the failure of the officer to advise the suspect of his right to counsel under CrRLJ 3.1or his Miranda rights prior to this questioning should result in suppression of this interview.

[32] DRE School Instructor Manual HS 172 R1/06 IV.

[33] State v. Baity, Id., at FN3, citing State v. Cissne, 72 Wn.App. 677, 68o, (1982). DRE School Instructor Manual HS 172 R1/06 IV 18-19.

[34] DRE School Instructor Manual HS 172 R1/06 IV-19.

[35] Id., at V-2. The Manual cautions “The formula can easily be “off” by 0.05 or more, even though the subject has consumed no drug other than alcohol.

[36] “...Three percent of 296 volunteers in a laboratory study had sufficient horizontal gaze nystagmus when sober to be mistaken for a BAC in the 0.08 to 010% range...” Moskowitz, H. Psychophysical Tests for DUI arrest, (1981) DOT-HS-8-01970, NHTSA report.

[37] DRE School Instructor Manual HS 172 R1/06 at V-3.

[38] DWI Detection and Standardized Field Sobriety Testing, HS 178 R2/06 P. 100-101; Validation of the Standardized Field Sobriety Test Battery at BACs Below .10 Percent, Stuster/Burns 1998, NHTSA DTNH22-95-C-05192 (1998).

[39] DRE Pre-School Instructor Manual HS 172A R1/06 III-18.

[40] DRE Pre-School Instructor Manual HS 172A R1/06 VI-3.

[41] DRE School Student Manual, HS 172 R4/93 VII-6.

[42] Prior to 2003 the protocol called additionally for checking the pupils under “indirect light.” The Instructor Manual states that this was eliminated “after research determined it had no direct correlation to impairment.” DRE Pre-School Instructor Manual HS 172A R1/06 IV-18.

[43] DRE School Instructor Manual HS 172 R1/06 IV-25.

[44] DRE School Instructor Manual HS 172 R1/06 IV-26.

[45] DRE Pre-School Instructor Manual HS 172A R1/06 II 12-13.

[46] DRE Student Manual, HS 172 R4/93 XXXVI-1.