Reply #17: I read recently that more than half of prison admits these days ...

[Fly by night]

... are folks on probation or parole (now called "supervised release") who are remanded to custody for violating the terms of their p/p. Generally for having a "dirty" pee-pee. (Sorry, don't have the link).

When I was in the federal Bureau of Prisons halfway houses, many of my fellow residents said that, although they preferred pot, they soon learned that they could use cocaine, meth, heroin, prescription mood-alterers and alcohol heavily on Friday night and be able to piss clean on Monday. But with cannabis, one joint put them at risk (for two weeks or more) of returning to the joint.

That is the one and only circumstance where I will admit that cannabis functions as a gateway drug.