The Full Faith and Credit clause is included in Article IV, Section 1 of the US Constitution. It establishes the duties of the states regarding the respect of public acts, records, and judicial proceedings conducted by other states within the Union.
According to the Supreme court there is a distinction about the credit owed to laws and to judgements. The latter are usually entitled to a greater respect than laws. Nowadays, the clause has little effect in the choice of law process. The choice of law takes place when there is a conflict between several legal systems and there is a need for reconciliation of legal documents from different jurisdictions, as it the case of the different legal systems of the federated states of the US.
This clause has be generarally applied in family law, for the issuing of orders of protection, to prevent violence against women and enhance children support.