Ex parte Mitsuye Endo, 323 U.S. 283 (1944), was a United States Supreme Court ex parte decision handed down on December 18, 1944, in which the Justices unanimously ruled that the U.S. government could not continue to detain a citizen who was "concededly loyal" to the United States. Although the Court did not touch on the constitutionality of the exclusion of people of Japanese ancestry from the West Coast, which it had found not to violate citizen rights in its Korematsu v. United States decision on the same date, the Endo ruling nonetheless led to the reopening of the West Coast to Japanese Americans after their incarceration in camps across the U.S. interior during World War II.

The Court also found as part of this decision that if Congress is found to have ratified by appropriation any part of an executive agency program, the bill doing so must include a specific item referring to that portion of the program.