Fauntleroy v. Lum
Supreme Court
210 U.S. 230 (1908)
Lum (defendant) lost money speculating in cotton futures and came to owe a debt to Fauntleroy (plaintiff), with the underlying transaction occurring in Mississippi. When Lum refused to pay, Fauntleroy won an arbitration award against him and then sued in Missouri to enforce it. The Missouri court, which had proper personal jurisdiction over Lum, refused to consider Lum's argument that the original transaction was illegal under Mississippi law and entered a directed verdict for Fauntleroy. Lum then persuaded the Mississippi Supreme Court that Missouri's judgment should not be enforced because it rested on an illegal Mississippi transaction, and Fauntleroy appealed to the U.S. Supreme Court.
Whether a state court must give full faith and credit to another state's judgment even when that judgment was based on a mistake of the enforcing state's own law.