From the Constitution of the United States:
Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State. And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof.
In the annotations for Article IV it shows that the inclusion of this clause in the US Constitution had it's roots in international laws and customs. I quote, in part, from the annotation:
http://caselaw.lp.findlaw.com/data/c...le04/01.html#1This comprises a body of rules, based largely on the writings of jurists and judicial decisions, in accordance with which the courts of one country, or ''jurisdiction,'' will ordinarily, in the absence of a local policy to the contrary, extend recognition and enforcement to rights claimed by individuals by virtue of the laws or judicial decisions of another country or ''jurisdiction.'' Most frequently applied examples of these rules include the following: the rule that a marriage which is good in the country [jurisdiction] where performed ( lex loci ) is good elsewhere;
This is very relevant related to same-gender marriage in the United States today. As we know Judge Joseph L. Tauro of the Federal Court of Boston has declared the Defense of Marriage Act unconstitutional based upon two Amendments to the US Constitution. In the case Judge Tauro ruled that the definition of marriage under DOMA of being exclusively related to marriage between a man and a woman violated the Commonwealth of Massachusetts rights under the 10th Amendment. Marriage has always been defined by state law and there was no legal precedent for the federal government to violate the state's rights in defining marriage. Judge Tauro also determined that the limitation by DOMA that the federal government deny benefits to same-sex couples violated the individual right of equal protection under the law established by the 14th Amendment. From Judge Tauro's decision:
The Obama adminstration originally appealed this decision but upon further review of the evidence it withdrew it's appeal. Since then the House Republicans retained legal services to re-instate the appeal. The first law firm the House Republicans hired, a very conservative law firm, later withdrew after reviewing the evidence presented in the initial court hearing. The House Republicans have retained a new law firm but the Court's decision is so well founded that all logical observers realize that there isn't a chance in hell of that the decision will be overturned."This court has determined that it is clearly within the authority of the Commonwealth to recognize same-sex marriages among its residents, and to afford those individuals in same-sex marriages any benefits, rights, and privileges to which they are entitled by virtue of their marital status," Tauro wrote. "The federal government, by enacting and enforcing DOMA, plainly encroaches upon the firmly entrenched province of the state."
When the legal dust settles the provisions in DOMA that limit marriage to a man and a woman is going to be declared unconstitutional and struck down. House Republicans are merely playing politics with the social conservatives because they know that DOMA is unconstitutional. That's why candidates for president like Mitt Romney signed a pledge to get a Constitutional amendment that would deny the recognition of same-sex marriage at the federal level. The fact that such an amendment would never be ratified isn't a concern to someone like Romney because he's merely putting on a show for the social conservatives.
Back to Article IV where one of the key considerations related to the full faith and credit clause is that a marriage in one jurisdiction (state) must be accepted by all other jurisdictions (states) in the United States. We have some states, such as N Carolina this week, which have gone so far as to ban same-sex marriage in their State Constitution but the US Constitution take precedent over all State Constitutions. With the demise of DOMA all states will have to give "full faith and credit" to every married couple that enters their state including same-sex couples married in states like Massachusetts.
While the N Carolina State Constitution states that they don't recognize same-sex marriage the US Constitution says that N Carolina must recognizes same-sex marriage if the individuals were married in a state which doesn't prohibit same-sex marriage. This is going to be true for every state regardless of whether they have a law or a state constitution which denies the recognition of marriage for same-sex couples as each of these must acknowledge that marriage under Article IV of the US Constitution.
This is going to cause another problem for these states. While they won't be issuing marriage licenses for same-sex couples, which is technically their legal right under the 10th Amendment, the fact that same-sex marriage for individuals married in other states must be recognized is going to create a case of denial of equal protection under the law for the State's own same-sex couples.
Once DOMA falls the prohibitions against same-gender marriage fall like a house of cards. Even state constitutional prohibitions have to fall to the authority of the US Constitution. We really must wonder why states are passing these laws and state constitutional amendments when they know that the denial of equal protection and the full faith and credit clause of the US Constitution are going to force them to accept same-sex marriage in the very near future.