As noted above, though; the OP has valid concerns. I personally don't have a problem with MJ and think it should be legal period. That's all irrelevant in the eyes of the law.
I wouldn't put a lot of stock in any legal advice dispensed on SDN. The odds are nothing will happen and if it does, it won't come back on you. However, no one can promise you that will be the case and if you get a drug rap it could prevent you from getting loans or screw with your license. Even if those two things aren't affected, you are still going to have to explain it on a residency application and that's
not ideal....
If it were me, I would just express my concerns to my room-mate. Tell him that he can do what he wants but that you are somewhat exposed in certain areas by being around illegal drugs (just so everything is understood up front) and then find a new room mate when your lease is up.
That's just my thought and tailored to the OP who expressed concerns about this. Obviously, many med students aren't concerned about it and are willing to assume the risk. That's a different story.
Again, I am not anti-MJ, but our thoughts on it's legality and/or benefits are irrelevant to the possible consequences.
On the legality issue of it and the "Dude, you aren't going to get caught as long as it stays inside" should take a few minutes to read this recent landmark SCOTUS case on search and seizure.
http://www.supremecourt.gov/opinions/10pdf/09-1272.pdf
Basically, the cops smelled pot, knocked on the door, heard people scuffling in what they perceived to be an attempt to dispose of the evidence, kicked the door in and busted a bunch of people for MJ possession. The Supreme Court ruled that it was a valid search and seizure.
Where did this happen? Lexington, Kentucky.
Isn't there a Medical School there?
I