President Trump’s recent executive order on immigration is already facing several legal challenges, despite the policy being only a few weeks old. At the time of this writing, the United States Circuit Court of Appeals has declined to grant a stay on a temporary restraining order suspending the order, and the Trump administration is preparing to issue a new order revising its immigration policies.

Trump’s executive order is drawing a lot of comparison to the executive order issued in 1942 by President Franklin D. Roosevelt, authorizing the Secretary of War to designate specific areas from which anyone could be excluded. The implementation of this authority saw Japanese-American citizens being given curfews, and later evacuated from their homes along the West Coast and placed into internment camps.

The Supreme Court heard a series of cases challenging the constitutionality of Roosevelt’s executive order, the most well-known being Korematsu v. United States, 323 U.S. 214 (1944). Fred Korematsu, a Japanese-American citizen affected by the order, challenged his conviction for violating the curfew and exclusion orders. He argued that the executive order granting the military this authority was an unconstitutional delegation of power, and that applying the order solely to Japanese-Americans qualified as unconstitutional racial discrimination. The government argued that the order was aimed at preventing wartime espionage and sabotage. The Court noted that although the singling out of Japanese-Americans was inherently suspect, it needed to be weighed against the protection of national security interests. The Court agreed with the government’s argument that because the military could not separate those disloyal to the United States, exclusion of all Japanese-American citizens was necessary. The Court found:

“Korematsu was not excluded from the Military Area because of hostility to him or his race. He was excluded because we are at war with the Japanese Empire, because the properly constituted military authorities feared an invasion of our West Coast and felt constrained to take proper security measures, because they decided that the military urgency of the situation demanded that all citizens of Japanese ancestry be segregated from the West Coast temporarily, and, finally, because Congress, reposing its confidence in this time of war in our military leaders — as inevitably it must — determined that they should have the power to do just this. There was evidence of disloyalty on the part of some, the military authorities considered that the need for action was great, and time was short.”

Though the Supreme Court has never officially overturned Korematsu, the U.S. District Court overturned the conviction decades later, after documents surfaced showing that a government report had exaggerated the threat of wartime espionage. The government generally has condemned the Korematsu ruling, acknowledging that the internment camps were a mistake, and enacting the Civil Liberties Act of 1988, which provided for reparations to be made to the people affected.

In his dissenting opinion, Justice Jackson wrote:

“Once a judicial opinion rationalizes such an order to show that it conforms to the Constitution, or rather rationalizes the Constitution to show that the Constitution sanctions such an order, the Court for all time has validated the principle of racial discrimination in criminal procedure and of transplanting American citizens. The principle then lies about like a loaded weapon, ready for the hand of any authority that can bring forward a plausible claim of an urgent need.”

Though at the time of this writing, no court has ruled on the merits of Trump’s executive order, it seems that courts are keeping this perspective in mind as they issue emergency motions and temporary restraining orders on Trump’s order, and Jackson’s statement may be an influence on future legal consideration of the order.