In the middle of the night, the Yuma County Sheriff’s Office received a request to investigate two suspicious people loitering near a residence. When questioned, the two individuals claimed they were hitchhiking. Marvin Timothy McElroy (defendant), one of the purported hitchhikers, asked the deputy sheriff for a ride into town. The deputy sheriff agreed but first conducted a pat down of McElroy, in compliance with standard procedure. The deputy sheriff discovered a plastic bag containing white pills in McElroy’s shirt. McElroy stated that the pills were amphetamines. After placing McElroy in the backseat of the patrol vehicle, the deputy sheriff discovered another bag containing white pills. When a field test showed that McElroy tested positive for amphetamines, McElroy was read his Miranda rights. McElroy again informed the deputy sheriff that the white pills were amphetamines. A chemist later determined that the pills were not amphetamines or any other dangerous drug prohibited by law. McElroy was convicted of attempted possession of dangerous drugs under Ariz. Rev. Stat. §§ 32-1996, 13-1001, 13-701, and 13-801. McElroy appealed on the ground that he could not be liable for attempted possession of dangerous drugs, because the lawful nature of the substance made it impossible for McElroy to be liable for the actual offense of possession of dangerous drugs.