Diversity Jurisdiction (28 U.S.C. § 1332)
“The district courts shall have original jurisdiction of all civil actions where the matter in controversy exceeds the sum or value of $75,000, exclusive of interest and costs, and is between … citizens of different States …”
Requirements
- Complete diversity — no plaintiff may share state citizenship with any defendant (Strawbridge v. Curtiss, 1806)
- Amount in controversy exceeds $75,000 (exclusive of interest and costs)
- Aggregation: single plaintiff against single defendant — may aggregate claims; multiple plaintiffs cannot aggregate to reach the threshold
- Legal certainty test (St. Paul Mercury Indemnity Co. v. Red Cab Co.): plaintiff’s demand controls unless it is legally certain that recovery cannot exceed $75,000
Citizenship Rules
| Party | Citizenship Rule |
|---|---|
| Individual (U.S. citizen) | State of domicile (physical presence + intent to remain) |
| Individual (alien) | Treated as citizen of the state in which admitted as permanent resident |
| Corporation | State of incorporation AND principal place of business (nerve center — Hertz Corp. v. Friend, 2010) |
| Unincorporated associations (LLP, LLC) | Citizenship of each member |
| Class actions | CAFA (28 U.S.C. § 1332(d)) — minimal diversity + $5M aggregate |
Complete Diversity Rule
Strawbridge v. Curtiss (1806): all plaintiffs must be diverse from all defendants. Even one non-diverse pairing destroys diversity.
Mas v. Perry (1974): domicile requires (1) physical presence and (2) intent to make that state one’s permanent home. Changed domicile requires presence plus intent simultaneously.