[University of California, San Diego, professor David A. Deitch talks about the lack of evidence connecting marijuana use and use of opiates and hallucinogenics].

David A. Deitch, a Clinical and Social Psychologist and currently a professor of Clinical Psychiatry at the University of California, San Diego, and director of the Addiction Training Center, speaks about the lack of direct evidence connecting marijuana use and use of opiates and hallucinogenics.