The California Supreme Court is hearing cases regarding whether or not a lesbian mother who has no biological connection to her child can receive joint or partial custody. Opponents of granting such rights argue that since one parent has no biological connection to the child, anyone who had a hand in raising the child or even planning the pregnancy could claim parental rights.
In this era of advanced reproductive technologies, the only person harmed by such ambiguity in the law is the newborn child that everyone says they want to protect. We know that "being a parent" isn't about the biological relationship, but the emotional relationship. Why remove that distinction when it comes to homosexual couples?