McCarran Walter Act of 1952
Note: McCarran and Walter were Democrats. This act was created in 1952 and used by Carter in 1979 ...
Trump was recently severely criticized for suggesting that the U.S. should limit or temporarily suspend the immigration of certain ethnic groups, nationalities, and even people of certain religions (Muslims). The criticisms condemned such a suggestion as, among other things, being "Un-American," dumb, stupid, reckless, dangerous and racist. Congressmen and Senators swore that they would never allow such legislation, and the president called such a prohibition on immigration unconstitutional.
As Gomer Pyle would say, "Surprise, Surprise !!!" It seems that the selective immigration ban is already law and has been applied on several occasions. Known as the McCarran-Walter Act, the Immigration and Nationality Act of 1952 allows for the "Suspension of entry or imposition of restrictions by president. Whenever the president finds that the entry of aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, the president may, by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrant’s or impose on the entry of aliens any restrictions he may deem to be appropriate."
The act was utilized by Jimmy Carter, no less, in 1979 to keep Iranians out of the United States, but he actually did more. He made all Iranian students already here check in, and then he deported a bunch. Seven thousand were found in violation of their visas, 15,000 Iranians were forced to leave the United States in 1979.
It is of note that the act requires that an applicant for immigration must be of good moral character and "attached to the principles of the Constitution." Since the Quran forbids Muslims to swear allegiance to the U.S. Constitution, technically, all Muslims should be refused immigration.