Can a person under the influence of an illegal drug be charged with possessing the drug?

[893 P.2d 720] As stated in Sullivan, supra, 234 Cal.App.2d at page 565, 44 Cal.Rptr. 524, if proof of ingestion of illegal drugs were sufficient to sustain a possession charge, then every person under the influence of an illegal drug could be charged with possessing it because, logically, one who ingests a drug must have possessed it at least temporarily. Yet it is arguable that not all occasions of drug use necessarily and inevitably involve criminal possession. For example, depending on the circumstances, mere ingestion of a drug owned or possessed by another might not involve sufficient control over the drug, or knowledge of its character, to sustain a drug possession charge. (See People v. Camp (1980) 104 Cal.App.3d 244, 247-248, 163 Cal.Rptr. 510 [essential elements of possession of controlled substance].)