Full faith and credit is the requirement, derived from Article IV, Section I of the Constitution, that state courts respect the laws and judgments of courts from other states. This clause attempts to prevent conflict among states and ensure the dependability of judgments across the country. This does so by requiring courts to follow the judgments made on the same issue in another state. Otherwise, individuals could simply go to another state to relitigate issues that did not receive favorable judgments in previous cases, and this would result in states having different judgments that could cause competition among states. Therefore, the full faith and credit clause prevents this kind of relitigation, under the doctrines of res judicata and issue preclusion, as long as the state issuing the original judgment had jurisdiction to do so. This same principle also applies to certain kinds of laws among different states like marriage.
While the full faith and credit clause typically applies, sometimes courts may disregard the judgments of other courts based upon the prior court not having jurisdiction or following constitutionally required procedures. For example, a court in New York may ignore the judgment from California where the defendant was never properly served.
[Last updated in December of 2022 by the Wex Definitions Team]