Not all legal experts think that the issue of reviewability is as cut-and-dried as you imply.
President claims extreme, sweeping powers to detain and deport without due process under wartime law from 1798.
www.brennancenter.org
Congress can repeal the Alien Enemies Act to safeguard against Trump's threat to conduct mass deportations without hearings.
www.justsecurity.org
I've seen no legal experts (aside from those associated with the WH) assert that the courts have no authority in this matter. I'd very much like to read the perspective of any independent experts who take Trump's side.
I have a confession to make.
I went back and read the statute. Back in 1798, federal statutes were a lot shorter.
Despite what Felix Frankfurter wrote in 1948,
the statute says:
"
§21. Whenever there is a declared war between the United States and any foreign nation or government, or any invasion or
predatory incursion is perpetrated, attempted, or threatened against the territory of the United States by any foreign nation or government,
and the President makes public proclamation of the event, all natives,
citizens, denizens, or subjects of the hostile nation or government, being of the age of fourteen years and upward,
who shall be within the United States and not actually naturalized,
shall be liable to be apprehended, restrained, secured, and removed as alien enemies. The President is authorized in any such event, by his proclamation thereof, or other public act, to direct the conduct to be observed on the part of the United States, toward the aliens who become so liable; the manner and degree of the restraint to which they shall be subject and in what cases, and upon what security their residence shall be permitted, and to provide for the removal of those who, not being permitted to reside within the United States, refuse or neglect to depart therefrom; and to establish any other regulations which are found necessary in the premises and for the public safety."
§22.[They should be given time to settle affairs and leave, if not guilty of a crime.]
§23. After any such proclamation has been made,
the several courts of the United States, having criminal jurisdiction, and the several justices and judges of the courts of the United States,
are authorized and it shall be their duty, upon complaint against any alien enemy resident and at large within such jurisdiction or district, to the danger of the public peace or safety, and contrary to the tenor or intent of such proclamation, or other regulations which the President may have established,
to cause such alien to be duly apprehended and conveyed before such court, judge, or justice;
and after a full examination and hearing on such complaint, and sufficient cause appearing, to order such alien to be removed out of the territory of the United States, or to give sureties for his good behavior, or to be otherwise restrained, conformably to the proclamation or regulations established as aforesaid, and to imprison, or otherwise secure such alien, until the order which may be so made shall be performed.
So, it appears that any enemy aliens who want to fight being expelled, can explain in court. So Trump really should have brought these people to court and let them explain.
Note, however, how Frankfurter characterized the law: "The very nature of the President's power to order the removal of all enemy aliens rejects the notion that courts may pass judgment upon the exercise of his discretion. This view was expressed by Mr. Justice Iredell shortly after the Act was passed."
That makes me wonder if Frankfurter interpreted the provisions of the Constitution with equal fidelity.
I think the INA give the president greater freedom from judicial restraint.