Constitutional Question (Either obvious or Arcane)

[RedSpartan]

4. This is correct.

The full faith and credit clause of the Constitution says that states must honor the laws of other states. That is why. for example, if you were married in, say, New Jersey and moved to California, you were also (in the eyes of the law) considered married in California without having to do it all over again.

DOMA, however, overrides this and says that states do not have to honor same-sex marriages performed in other states. It is unquestionably unconstitutional.

So in answer to your question, states can legislate to honor marriages from other states, but there is no reason to because it is already engrained in the Constitution. There is no problem with doing so, however, since it is consistent with the Constitution anyway.