No drugs in the theatre. Period.
I totally agree that what you do in your own time is your own business.
But be it booze, pot, coke, or anything more colorful, it will affect your work performance and the safety of your colleagues. And the important word here is SAFETY. Coke will not help make a load-out go faster. Pot will not make the sound board operator come up with a brilliant new mix. The alcoholic choreographer is not more graceful when her iced tea is heavily laced with vodka. Drugs [in the workplace] are bad, m'kay?
I have been in many student, community, and professional theatres where this issue has come up. While always being clear that I will not tolerate drug use, possession, or intoxication in the workplace, I do not kick and scream about it in general. (Sort of how when parents kick and scream the kid only gets more curious about drugs and other mischief...) If someone is identifiably under the influence, they are fired. If I smell something fishy, I grab the TD and/or house SM if it regards crew (who usually knows
exactly what's going on, whether or not s/he is involved), or the director or Artistic Director if it's the cast, and request that the smell be erased and all crew informed that drug use or possession in the workplace will result in immediate termination. Be professional. Draw the hard line. And you'll be respected for it because you're keeping everyone SAFE.
A true story form a professional IATSE house... most of the crew were out in the theatre alley smoking a joint at intermission. The cops came and arrested them. When we came back from intermission, we didn't have enough crew to make the scene changes in Act II. Besides **SAFETY**, this is one example how drugs can wreak havoc on your theatre.
If you need to know more about how to identify people who might be under the influence (because you'd better be 150%+ sure before you fire them), check out
www.erowid.org, where you'll find encyclopedic listings of effects, behavior, tolerance, smell/taste, and all sorts of other things about nearly every drug ever, complete with personal experience posts that can be informative, amusing, and sometimes downright scary. And if you do need to dismiss someone while they're under the influence, be sure to have some big guys around, and let them know what's about to happen (but don't be unnecessarily intimidating, just make sure they're in the room). Usually, it will pass without incident. But sometimes, people on drugs can get very angry and strong and scary when you do things like fire them.