Uphold the Immigration and Nationality Act of 1952 and Public Law 414

Uphold the Immigration and Nationality Act of 1952, Public Law 414, with particular focus on Chapter 2 Section 212. https://www.gpo.gov/fdsys/pkg/STATUTE-66/pdf/STATUTE-66-Pg163.pdf
This law "prohibits entry to the US if the alien belongs to an organization seeking to overthrow the government of the United States by violence, force, or other unconstitutional means." This law is particularly applicable to denying entry to members of known terrorist organizations such as ISIS or Al-Qaeda and others.