Short Answer 
Roosevelt’s Executive Order No. 9066, driven by fears of espionage after Pearl Harbor, led to the mass relocation of over 110,000 Japanese Americans to internment camps, reflecting significant civil rights violations. The Supreme Court upheld the order, reinforcing governmental claims of national security threats and highlighting the prevailing distrust towards Japanese Americans during World War II.
Step 1: Understanding the Assumption
The core assumption in Roosevelt’s Executive Order No. 9066 is the perceived high risk of espionage and sabotage from Japanese Americans. This assumption arose during a time of heightened national tension due to World War II and specifically the attack on Pearl Harbor by Japan. This context created a climate of distrust towards Japanese Americans, leading to fears about their loyalty and potential espionage activities.
Step 2: Implementation of the Order
The Executive Order authorized the mass relocation of Japanese Americans to internment camps under the justification of national security. The order allowed military leaders and the Secretary of War to deem individuals as threats and exclude them from designated military areas. As a consequence, over 110,000 Japanese Americans were forcibly removed from their homes, marking a significant violation of civil rights during wartime.
Step 3: Legal and Historical Context
This executive action was subsequently upheld by the Supreme Court, which reinforced the government’s stance on internal threats during wartime. The legal backing provided a justification for the internment of Japanese Americans, deepening the impact of the assumptions held about their loyalty and the overall security of the nation. Understanding this historical context is crucial for recognizing the implications of Executive Order No. 9066.