What are some constitutional principles related to same-sex marriage?

Answer 1

Some constitutional principles that might be applied to the issue of same-sex marriage are: the equal protection clause, the full-faith-and-credit clause, the separation of church and state and the freedom of religion. It is important to note that marriage is not explicitly mentioned in the US Constitution.

Answer 2

Same-sex marriage is constitutional because under the US Constitution, individual states have the right to pass their own marriage laws, including those legalizing same-sex marriage. Now, if your question is how is same-sex marriage MANDATED by the constitution, well ... it isn't, at least not explicitly. However, laws limiting marriage to heterosexual couples have been struck down by state supreme courts as unconstitutional. The final decision on interpreting the constitution on this issue rests with the US Supreme Court.