In 1941 the Japanese American population of the United States consisted primarily of two groups: foreign-born immigrants, called Issei; and their American-born children, the Nisei. After the bombing of Pearl Harbor, both groups were classified as enemy aliens. Although the nation was also at war with Germany and Italy, the native-born Italian and German Americans faced little hostility or public reprisals.
President Franklin D. Roosevelt became concerned about Japanese Americans living in California. In November, 1941, Roosevelt asked John Franklin Carter, who ran the White House intelligence unit, was requested to investigate fifth column infiltration, particularly by Japanese living on the West Coast, whether American citizens or aliens. Carter sent a Chicago businessman, Curtis B. Munson. He later reported: "There are still Japanese in the United States who will tie dynamite around their waist and make a human bomb of themselves... But American-born Japanese were... universally estimated from 90 to 98 per cent loyal to the United States... They are very American and are of a proud, self-respecting race suffering from a little inferiority complex and a lack of contact with the white boys they went to school with."
After Pearl Harbor Roosevelt decided that he needed to take action against Japanese Americans. On 29th January 1942, the U.S. Attorney General, Francis Biddle, established a number of security areas on the West Coast in California. He also announced that all enemy aliens should be removed from these security areas. Three weeks later President Franklin D. Roosevelt authorized the construction of relocation camps for Japanese Americans being moved from their homes. Over the next few months ten permanent camps were constructed to house more than 110,000 Japanese Americans that had been removed from security areas. These people were deprived of their homes, their jobs and their constitutional and legal rights.
In July 1942 Mitsuye Endo, a Nisei, petitioned for a writ of habeas corpus on the grounds that detention in a relocation camp was unlawful. In December 1944 the Supreme Court ruled in her favour and over the next few weeks the Japanese Americans in the camps returned to their homes in California.