(plaintiffs, homosexual males, cannot be named on birth certificate of child they adopted in New York; state (LA) law bars all unmarried couples (whether adopting in-state or out-of-state) from adopting children in Louisiana - child was born in LA and plaintiffs living in CT at time emergency adoption decree obtained in NY state court; defendant, LA registrar, offered to list one plaintiff on birth certificate, but plaintiffs refused alleging violation of constitutional rights; no violation of either Full Faith and Credit Clause or Equal Protection Clause; state law does not necessarily operate as that state's law when it is attempted to be applied by another state - the manner in which LA enforces out-of-state adoptions does not deny plaintiffs' full faith and credit of other state's law; LA's treatment of adoptive children of unmarried persons differently from adoptive children of married persons does not violate equal protection, but serves a legitimate governmental interest and the state's rational preference for stable adoptive families - the state can rationally conclude that having parenthood focused on a married couple or single individual rather than the freely severable relationship of unmarried persons furthers the interests of adopted children).