Experimental: Opioid Agonist/Marijuana Combination
Participants will receive non-therapeutic, experimental doses of active opioid/placebo in combination with non-therapeutic, experimental doses of active vaporized marijuana/placebo. Opioid/placebo and marijuana/placebo doses will be administered once during each session. It is possible to receive both active drugs on the same day. Opioid doses will be administered intranasally; marijuana doses will be administered via vaporizer.
Drug: Vaporized Marijuana
Active Marijuana or Placebo, administered through vaporizer
Other Name: Cannabis
Drug: Opioid Agonist
Active Opioid Agonist or Placebo, administered intranasally