It doesn't effect me one way or the other of John Doe get's his ears pierced or his hair dyed orange. On the other hand it does effect me, and everyone else, if TB positive John Doe refuses medication b/c he claims a "Constitutional right" to his own body...well, there you cross the line.
This was driven home by Supreme Court Justice Oliver Wendell Holmes, Jr. at the turn of the last century agreed with the majority of the Court in its decision to permit forced steralization of retarded people.
The case had to do with three generations in one family of "idoits" (in the legal sense, person w/ IQ's between 60-85 I believe) who kept having idoitic(retarded) babies and still more babies, till at last all three generations had become a terrible burden on the community. "Three generations of idoits," declared Holmes for the Court, "are enough."
IOW, individual "rights" do not,and should not, trump the common rights of all.