I’m not a lawyer, but I’ll take a stab at this.
From what I remember in college, our written constitution is based upon English common law, which recognized only marriage between men and women. Not that many same sex couples, circa 1350 AD, applied at the local village hall–or the local parish–to get married. Anyway, since neither our constitution, or any laws short of Vermont’s recent “Civil Union” legislation, addressed this matter, gays/lesbians cannot get married and have it recognized by any legal authority in the USA.
In short, same sex couples can’t get married, since no one ever said they can. Again, I’m not a lawyer, but I think got to the heart of that matter.
Pot and booze. I’ll turn this one around. Let’s say that I invented alcoholic beverages in my basement last year. Prior to that, it never existed. Once I perfected my “invention,” my friends and I would drink it daily, and we loved the inhibition-releasing effects of beer and wine etc., the buzz, not to mention the great feeling of being totally blasted, peeing off the balcony while blitzed, etc. Now, let’s see one of my friends says: “Dude, ya gotta sell this stuff!” I do. And then the FDA gets wind of my new business venture. They do studies. They find that people who drink my “invention” cannot act responsibly, drive a car as well as when NOT drinking my invention, “operate heavy machinery,” or avoid picking fights with people. Not to mention the problems that come after drinking such as hangovers, the risk of addiction–and later on–liver damage, throat cancer, etc.
My “invention,” if not banned outright, would be available only under prescription.
Then why is booze legal and pot not? Because, kind of like marriage and English common law, etc, booze–except for the foolish detour during the 1920s–has been legal since our ancestors wore fur for underwear. And sociey accepts alcohol, for the most part.
Hope I made this a little clearer.