The rating procedure was developed by the Los Angeles Police Department for use in detecting drug-impaired drivers. Eight drug conditions were assessed in the laboratory evaluation of the procedure: d-amphetamine, 15 or 30 milligrams (mg) orally; diazepam, 15 or 30 mg orally; secobarbital, 300 mg orally; and marijuana, 12 puffs of 1.3 or 2.8 percent tetrahydrocannibinol. Drug doses were administered three times to allow for differing absorption rates. The procedures showed a high degree of accuracy in correctly identifying the drug classes administered to subjects judged to be intoxicated. Of subjects judged intoxicated, the correct class was identified on 91.7 percent occasions. In 98.7 percent of intoxication judgments, the subject had received some active drug. On 7 percent of occasions of judged intoxication, the incorrect drug class was identified. Finally, on 1.3 percent of occasions, the subject had received no active drug, for a false positive rate of 8.3 percent. Sensitivity of the procedure was directly related to the administered dosage: as dose increased, detection and identification of intoxication increased. Tables, graphs, and figures.