Korematsu v. United States was a landmark decision enacted by the US Supreme Court in 1944 and it was related to constitutionality of the process of internment of US Japanese citizens (those with full or partial Japanese descent) in camps during the war, that was performed after the approval of the Executive Order 9066.
The Court backed the goverment's decision and claimed that the executive order was constitutional. They argued that the national interest of ensuring protection over espionage outweighed the rights of US citizens with Japanese descent.