So my take is thus:

Yeah, I smoked a bunch when I was younger. Yes, it does slow you down mentally. Yes, it can cause memory loss. Is it any more dangerous than cigarettes? My reading has led me to believe no, in terms of the various substances ingested from it, and being a carcinogen.

As an individual, I really could care less if people want to do it on their own personal time. I don't view it as any worse that alcohol or cigarettes in terms of real and potential damage one can do to oneself and to others directly and indirectly. It's just something I enjoyed doing because of the feeling it gave me, quit absolute cold turkey after a 10 second decision, and never had any regrets or problems doing so (ie. I was not remotely addicted). In short, I just grew out of it.

This next bit is a kinda tricky, and I'm still not sure I have a good solution or final opinion yet, but...

As a businessman and employer, I can't help but want the ability to discriminate based on drug usage. The simple reason is because it does affect performance. Sorry, but one is not going to be able to go out and smoke a bowl on break, then come back in and be as productive as they once were. Weed makes you tired, mellow, gives you the munchies, etc. Other drugs have other effects but it all boils down to being able to concentrate and get the job at hand done. Of course this isn't a 100% airtight argument, some things affect people differently, but I firmly believe that at it's core my argument is solid, re: productivity. Now this does conflict somewhat with my "I don't care if you do it in the privacy of your own home", and this is where I haven't been able to entirely resolve those two. Most businesses have policies against drug usage; come in to work drunk or hopped up on something, and you'll get escorted out the door, and I'm fine with this. So it would seem that the break-even point here is that what you do on your own time at home is off limits to an employer, but if you come into work under the influence of something, then all bets are off and you're risking your job in doing so. /shrug