The U.S. Constitution enjoins each state to accord “full faith and credit” to “the public acts, records, and judicial proceedings of every other State”. U.S. Const. Art. IV, § 1. However, a judgment creditor can’t directly enforce a judgment obtained in another state in California. The other state’s judgment must first be turned into a California judgment. The statutory mechanism for effecting this is the Sister State and Foreign Money—Judgments Act, aka the SSFMJA, Code Civ. Proc. § 1710.10 et seq.