Answer:
It was a matter of national security, pure emergency in a time of war. In February 1942, President Franklin D. Roosevelt approved an executive order whereby the Army could evict anyone considered a risk from their homes and detain them in concentration camps. Little more than two months had passed since Japan's attack at the Pearl Harbor base in Hawaii, and Washington wanted to prevent espionage or sabotage in military sensitive areas at all costs. The measure resulted in the expulsion from the west coast of the United States of those citizens of Japanese origin, including those with US nationality. More than 100,000 ended up in a detention center in the interior of the country. One of those expelled, Fred Korematsu, protested and was convicted of disobeying the military order. The case reached the Supreme Court, which in 1944 ruled in favor of this policy in the name of defense and protection at an exceptional time, establishing that citizenship, protected by the Fourteenth Amendment, cedes their rights against common national security to all the inhabitants of the country.