Philosophy
Preclusion and the Jurisdictional Limits of State Court Litigation
Quick fact
The Full Faith and Credit Clause requires every state to recognize and enforce judgments from other states, so a valid state court judgment can bar relitigation of the same case in any U.S. court, including federal courts.
Why this is interesting
You won a lawsuit in a state court, but the other side thinks they can just try again in another court. Are they allowed to?