| Litigants: | Duncan v. Kahanamoku |
| Arguedate: | December 7 |
| Argueyear: | 1945 |
| Decidedate: | February 25 |
| Decideyear: | 1946 |
| Fullname: | Duncan v. Duke Kahanamoku, Sheriff |
| Usvol: | 327 |
| Uspage: | 304 |
| Parallelcitations: | 66 S. Ct. 606; 90 L. Ed. 688 |
| Prior: | Ex parte Duncan, 146 F.2d 576 (9th Cir. 1944); cert. granted, . |
| Holding: | Duncan's trial by military tribunal was not authorized by the Hawaiian Organic Act. |
| Majority: | Black |
| Joinmajority: | Reed, Douglas, Murphy, Rutledge |
| Concurrence: | Murphy |
| Concurrence2: | Stone |
| Dissent: | Burton |
| Joindissent: | Frankfurter |
| Notparticipating: | Jackson |
Duncan v. Kahanamoku, 327 U.S. 304 (1946), was a decision by the United States Supreme Court. It is often associated with the Japanese exclusion cases (Hirabayashi v. United States, Korematsu v. United States and Ex parte Endo) because it involved wartime curtailment of fundamental civil liberties under the aegis of military authority,[1] though in this case neither the plaintiff nor the nominal defendant were Japanese.
While Duke Kahanamoku was a military police officer during World War II, he arrested Lloyd C. Duncan, a civilian shipfitter on February 24, 1944, after Duncan's brawl with two armed Marine sentries at the yard. At the time, Hawaii was not yet a state and was administered under the Hawaiian Organic Act. After the attack on Pearl Harbor, the Governor of Hawaii suspended the writ of habeas corpus and placed the territory under martial law.
Duncan was tried and convicted by a military tribunal for assault on military or naval personnel with intent to resist or hinder them in the discharge of their duty. However, civilian courts had restarted summoning jurors and witnesses and conducting criminal trials on the island.
Duncan appealed to the Supreme Court, which ruled that his trial by military tribunal was not authorized by the Hawaiian Organic Act.