This has probably been addressed somewhere, but what about Full faith and credit clause (Art IV, section 1) of the U.S. Constitution which provides that the various states must recognize judicial decisions of the other states within the United States. See Black's Law dictionary 5th edition.

Or the Fauntleroy Doctrine; see Black's law dictionary 5th ed.

Does it matter which state ruled as long as it was in a court equal to or higher than the court you are currently in?