Are you American? I assume yes in which case the constitution gives the ability. The US is sort of a democracy now but even if it reverted to the 1800 laws, it still has the ability to regulate what you can and can't do with your own body.
I asked what right. You keep spouting about property rights, but do you really believe in them?
Check your question:
Tell me what right gives them the ability to tell me what I can and cannot do with my body, and I will gleefully become a proponent of democracy, and renounce this "silly anarchist view".
By what right does one man inherits billions of dollars while another inherits nothing? Americans have the right to choose their government the exact same way.
By what rihgt do they intrude upon and violate my property rights, in the very sanctum of the most basic property I own, my own body?
Are you asking me to read the us constitution? The only part I really bothered with was the second amendment :S Or are you asking why the constitution has any right to be treated as valid?