Q:

What is the legal source of the banned immigrants list?

The recent presidential decree banning immigrants from certain nations refers to 8 USC 1187(a)(12), identifying aliens "from countries referred to in" that piece of law, which explicitly names Syria and Iraq as being on the list. The law also states that other countries might be put on the list, but does not name others. The decree itself does not list any specific countries as being on the banned list, but there seems to be media agreement that the list of seven includes Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen; it also does not include Cuba or North Korea. The relevant pieces of US Code indicate that the Secretaries of State or Homeland Security might maintain such lists, but I can't find clear and current evidence of any such list from which these nations could be identified. The list of countries seems to closely correspond to earlier versions of the "State Sponsors of Terrorism" list, but omits North Korea and includes states which were formerly but are not currently on the list.
Is there any currently-valid government list which identifies Iran, Libya, Somalia, Sudan and Yemen (and optionally Iraq and Syria), and no other countries, in a fashion that can be subsumed under the provisions of 8 USC 1187(a)(12)? And, of course, a legally-authoritative source of the list would be needed. 

A:

Looks like 217(a)(12) of the INA, as referenced in the EO (codified as 8 USC 1187(a)(12)), refers to a list of countries/areas of concern requiring enhanced scrutiny for the visa waiver program under the DHS/U.S. Customs and Border Protection (CBP)-009 Electronic System for Travel Authorization (ESTA) System of Records. Iraq and Syria are in the statute. DHS maintains the list.  They added Somalia, Yemen, and Libya to the list on 6/17/2016 in 81 FR 39680. Iran and Sudan were added previously.

