Migra v. Warren City School District Board of Education

Under 28 U.S.C. § 1738, a state-court judgment has the same claim-preclusive (res judicata) effect in a subsequent federal 42 U.S.C. § 1983 action as it would have in the courts of the rendering state, so § 1983 plaintiffs cannot relitigate in federal court claims that were or could have been raised in prior state litigation.