“The gateway analogy evokes two ideas that are often confused. The first, more often referred to as the ‘stepping stone’ hypothesis, is the idea that progression from marijuana to other drugs arises from pharmacological properties of marijuana itself.

The second is that marijuana serves as a gateway to the world of illegal drugs in which youths have greater opportunity and are under greater social pressure to try other illegal drugs.”

Mar. 1999 - “Marijuana and Medicine: Assessing the Science Base”