The basis of the Roe decision.
But what is it?
From the Cornell Law School:
1) The right not to have one's personal matters disclosed or publicized; the right to be left alone. 2) The right against undue government intrusion into fundamental personal issues and decisions. Although the U.S. Constitution does not explicitly state that there is a right to privacy, Supreme Court decisions have found an implicit constitutional right to privacy in striking down laws that criminalize sodomy, the use of contraceptives, and abortion.
