The 
Immigration and Nationality Act of 1952 (
Pub.L. 82–414, 66 
Stat. 163, enacted June 27, 1952), also known as the 
McCarran–Walter Act, restricted immigration into the U.S. and is codified under 
Title 8 of the United States Code (
8 U.S.C. ch. 12). The Act governs primarily immigration to and citizenship in the United States. It has been in effect since December 24, 1952.
The Act was sponsored by two Democrats; H.R. 5678 was named after its sponsors, Senator 
Pat McCarran (D-
Nevada), and Congressman 
Francis Walter (D-
Pennsylvania).
Speaking in the Senate on March 2, 1953, the Democrat, McCarran, said (
Senator Pat McCarran, Cong. Rec., March 2, 1953, p. 1518):
I believe that this nation is the last hope of Western civilization 
and if this oasis of the world shall be overrun, perverted, contaminated
 or destroyed, then the last flickering light of humanity will be 
extinguished. I take no issue with those who would praise the 
contributions which have been made to our society by people of many 
races, of varied creeds and colors. ... However, we have in the United 
States today hard-core, indigestible blocs which have not become 
integrated into the American way of life, but which, on the contrary are
 its deadly enemies. Today, as never before, untold millions are 
storming our gates for admission and those gates are cracking under the 
strain. The solution of the problems of Europe and Asia will not come 
through a transplanting of those problems en masse to the United States.
 ... I do not intend to become prophetic, but if the enemies of this 
legislation succeed in riddling it to pieces, or in amending it beyond 
recognition, they will have contributed more to promote this nation's 
downfall than any other group since we achieved our independence as a 
nation. 
America is the last hope of Western 
Civilization and if overrun by any creed (such as Islamism) or any race 
(i.e., Hispanic or others) that does not assimilate or are enemies of America the 
nation will decline as a result.
In fact, 
Federal law does permit a president to ban those who are deemed security risks from entering the country. The relevant passage states:
"Whenever
 the President finds that the entry of any aliens or of any class of 
aliens into the United States would be detrimental to the interests of 
the United States, he 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 nonimmigrants, or impose on the entry of aliens 
any restrictions he may deem to be appropriate. Whenever the Attorney 
General finds that a commercial airline has failed to comply with 
regulations of the Attorney General relating to requirements of airlines
 for the detection of fraudulent documents used by passengers traveling 
to the United States (including the training of personnel in such 
detection), the Attorney General may suspend the entry of some or all 
aliens transported to the United States by such airline."
Cf. https://www.law.cornell.edu/uscode/text/8/1182
During the latest controversy over immigration, Khizr Khan spoke alongside his wife Ghazala Khan at the Democratic National Convention. On
 behalf of Hillary Rodham Clinton, the Democratic nominee for president,
 Khizr Khan questioned Donald Trump’s policies on 
immigration—specifically his plan to bar Muslim migration from regions 
afflicted with rampant terrorism into America temporarily until the 
United States can figure out the situation.
Khan
 brought out a pocket Constitution, claiming inaccurately that Trump’s 
plans were unconstitutional. That’s not true, as Congress has already 
granted such power to the president under
 the Immigration and Nationality Act of 1952—allowing the president to 
bar migration of any alien or class of aliens the president sees as a 
threat to the United States for any reason at any time. Such a class of 
aliens could be Muslims, or it could be people from a specific region of
 the world, or any other class—such as someone’s race, weight, height, 
age, national origin, religion, or anything else.