The Congressional Research Service is the Non-Partisan Agency tasked with studying issues for members of Congress.
On January 23, 2017 CRS published Executive Authority to Exclude Aliens [Non U.S. Citizens]: In Brief by Kate M. Manuel, Acting Section Research Manager
Former House Judiciary Committee Immigration Law Expert Nolan Rappaport wrote an extraordinarily prescient article mirroring the CRS findings above. It can be found here.