The recent attacks in Paris and San Bernardino have led to an increase in anti-Islamic rhetoric in the U.S. There have been calls to limit the immigration of Muslims. Some have focused as well on the threat from within, arguing for the registration of all Muslims—or even their internment, as with the camps where Japanese Americans were sent during World War II.  From the inception of the United States, our government has put in place measures to determine who belongs to this great experiment and who does not.