Civil Procedure
Jurisdiction first
Every Civil Procedure question starts with two gates. Subject-matter jurisdiction: federal question under §1331, diversity under §1332 (complete diversity plus more than $75,000 in controversy), and supplemental jurisdiction under §1367. In diversity cases §1367(b) blocks supplemental claims by plaintiffs against parties joined under Rules 14, 19, 20, or 24 that would destroy diversity. Personal jurisdiction: a state long-arm statute plus due process - purposeful availment, relatedness, and fairness. Specific jurisdiction needs the claim to arise out of or relate to the contacts; general jurisdiction requires the defendant to be at home (state of incorporation and principal place of business for corporations).
Erie and the substance/procedure line
A federal court sitting in diversity applies state substantive law and federal procedural rules valid under the Rules Enabling Act. Characterization is the trap: statutes of limitations are usually substantive, while burden of proof and discovery scope are contested.
Preclusion
Claim preclusion requires a final judgment on the merits, the same claim, and the same parties or their privies. Issue preclusion requires an issue actually litigated, necessary to the judgment, and asserted against a party with a full opportunity to litigate. Nonmutual offensive estoppel raises fairness concerns.
Worked example
A plaintiff sues a diverse defendant for $100,000 and adds a $20,000 state-law claim against a nondiverse co-defendant. Diversity exists for the first claim; the second cannot ride along because §1367(b) bars supplemental jurisdiction over claims by plaintiffs against nondiverse joined parties.
Rule of thumb: identify the statute before the constitutional test, and check §1367(b) every time diversity appears.