#18 The Smith Act Of 1940
At the time of the Second World War, the United States faced heat waves from within. As it became more and more obvious that the United States would ultimately indulge in the war, lawmakers drafted a law to protect the country from breaking into a civil war.
The Alien Registration Act of 1940 (colloquially referred to as the Smith Act) was passed to oppose any rebellion against the government. Under the act, it was mandatory for the non-citizens (aliens) to file their complete details with the government. Those who defaulted or were found guilty of opposition were deported.