Korematsu v. United States , was a landmark United States Supreme Court case concerning the constitutionality of Executive Order 9066, which required Japanese-Americans in the western United States to be excluded from a described West Coast military area.

In a 6-3 decision, the Court sided with the government, ruling that the exclusion order was constitutional. The opinion, written by Supreme Court justice Hugo Black, held that the need to protect against espionage outweighed Fred Korematsu's individual rights, and the rights of Americans of Japanese descent.

Indeed, Korematsu's conviction for evading internment was overturned on November 10, 1983, after Korematsu challenged the earlier decision by filing for a writ of coram nobisis a petition to the court in its capacity of a Court of Equity to correct a previous error "of the most fundamental character" to "achieve justice" where "no other remedy . In a ruling by Judge Marilyn Hall Patel, the Federal District Court for the Northern District of California granted the writ (that is, it voided Korematsu's original conviction) because in Korematsu's original case, the government had knowingly submitted false information to the Supreme Court that had a material impact on the Supreme Court's decision.