The Drug Recognition Expert is trained to recognize signs of impairment in seven different categories of illegal drugs, based upon their observations.

The program was developed in the early 1970s initially by the Los Angeles Police Department. The program was eventually expanded to other states and countries. The program relies heavily on standardized field sobriety testing, but when used fully, it includes additional testing, including physical, blood alcohol and urine testing.

Today, the Drug Evaluation and Classification Program is in use in all 50 states, the District of Columbia, Canada and the UK.

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The DREs are able to identify symptoms of impairment in these categories:

1. Central Nervous System (CNS) Depressants

CNS depressants slow down the operations of the brain and the body. Examples of CNS depressants include alcohol, barbiturates, anti-anxiety tranquilizers (e.g., Valium, Librium, Xanax, Prozac, and Thorazine), GHB (gamma hydroxybutyrate), Rohypnol, and many other anti-depressants (e.g., Zoloft, Paxil).

2. CNS Stimulants

CNS stimulants accelerate the heart rate and elevate the blood pressure and “speed-up,” or over-stimulate, the body. Examples of CNS stimulants include cocaine, “crack” cocaine, amphetamines, and methamphetamine (“crank”).

3. Hallucinogens

Hallucinogens cause the user to perceive things differently than they actually are. Examples include LSD, peyote, psilocybin and MDMA (Ecstasy).

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4. Dissociative Anesthetics

Dissociative anesthetics include drugs that inhibit pain by cutting off or dissociating the brain’s perception of the pain. PCP, its analogs, and dextromethoraphan are examples of dissociative anesthetics.

5. Narcotic Analgesics

Narcotic analgesics relieve pain, induce euphoria, and create mood changes in the user. Examples of narcotic analgesics include opium, codeine, heroin, demerol, darvon, morphine, methadone, Vicodin, and oxycontin.

6. Inhalants

Inhalants include a wide variety of breathable substances that produce mind-altering results and effects. Examples of inhalants include Toluene, plastic cement, paint, gasoline, paint thinners, hair sprays, and various anesthetic gases.

7. Cannabis

Cannabis is the scientific name for marijuana. The active ingredient in cannabis is delta-9 tetrahydrocannabinol, or THC. This category includes cannabinoids and synthetics like Dronabinol.