Joseph Story, Commentaries on the Constitution 3:§§ 1298--1307
§ 1302. The clause of the constitution propounds three distinct objects; first, to declare, that full faith and credit shall be given to the records, &c. of every other state; secondly, to prescribe the manner of authenticating them; and thirdly, to prescribe their effect, when so authenticated. The first is declared, and established by the constitution itself, and is to receive no aid, nor is it susceptible of any qualification by congress. The other two are expressly subjected to the legislative power.
§ 1305. The next section of the clause is, "And the congress may by general laws prescribe the manner, in which such acts, records, and proceedings shall be proved, -- and the effect thereof." It is obvious, that this clause, so far as it authorizes congress to prescribe the mode of authentication, is wholly beside the purpose of the preceding. Whatever may be the faith and credit due to the public acts, records, and proceedings of other states, whether primâ facie evidence only, or conclusive evidence; still the mode of establishing them in proof is of very great importance, and upon which a diversity of rules exists in different countries. The object of the present provision is to introduce uniformity in the rules of proof, (which could alone be done by congress.) It is certainly a great improvement upon the parallel article of the confederation. That left it wholly to the states themselves to require any proof of public acts, records, and proceedings, which they might from time to time deem advisable; and where no rule was prescribed, the subject was open to the decision of the judicial tribunals, according to their own views of the local usage and jurisprudence. Many embarrassments must necessarily have grown out of such a state of things. The provision, therefore, comes recommended by every consideration of wisdom and convenience, of public peace, and private security.
§ 1307. ... The act of 26th of May, 1790, (ch. 11,) after providing for the mode of authenticating the acts, records, and judicial proceedings of the states, has declared, "and the said records and judicial proceedings, authenticated as aforesaid, shall have such faith and credit given to them in every court within the United States, as they have by law or usage in the courts of the state, from whence the said records are or shall be taken." It has been settled upon solemn argument, that this enactment does declare the effect of the records, as evidence, when duly authenticated. It gives them the same faith and credit, as they have in the state court, from which they are taken. If in such court they have the faith and credit of the highest nature, that is to say, of record evidence, they must have the same faith and credit in every other court. So, that congress have declared the effect of the records, by declaring, what degree of faith and credit shall be given to them. If a judgment is conclusive in the state, where it is pronounced, it is equally conclusive every where. If re-examinable there, it is open to the same inquiries in every other state. It is, therefore, put upon the same footing, as a domestic judgment.