Not Quite, Doc

You'd think an expert opinion might indeed be forthcoming from a man with these qualifications: 

John D. Bessler is a law professor at the University of Baltimore School of Law, an adjunct professor at the Georgetown University Law Center and a visiting scholar at the University of Minnesota Law School’s Human Rights Center.

I wanted to agree with him, because as you know I also have 8th Amendment concerns about Trump and especially his stated intention to deliver American citizens to foreign prisons. However, the professor's logic doesn't work.

The Eighth Amendment’s ban on cruel and unusual punishment prohibits this course of action. White House lawyers should read the U.S. Supreme Court’s landmark decision in Trop v. Dulles. The court barred the government from rendering U.S. citizens stateless, which is similar to what Trump is threatening to do if Americans are imprisoned abroad.

During World War II, Albert Trop, an American citizen, was serving as a U.S. Army private in Morocco. He escaped a stockade and was taken into custody the next day and court-martialed. Convicted of desertion, he was sentenced to three years of hard labor, forfeiture of pay and a dishonorable discharge. When Trop applied in 1952 for a passport, his application was denied on the ground that, under the Nationality Act of 1940, he had lost his U.S. citizenship by virtue of his conviction.

In Trop, the Supreme Court held that denationalization as a punishment is a violation of the cruel and unusual punishments clause of the Eighth Amendment....The Trop case makes clear that any effort to incarcerate U.S. citizens abroad would be an Eighth Amendment violation. Were that to happen, people would — as a practical matter — be deprived of their fundamental constitutional rights. 

Apparently the professor missed the part of his own story in which Trop was incarcerated in Morocco. That wasn't an issue for the court. They just said that he couldn't be denaturalized. Trump hasn't proposed denaturalizing American citizens, just having them incarcerated outside the territorial USA. Trop was so incarcerated himself, presumably by the US Army but there's no reason the prison couldn't be run by foreign contractors instead of American soldiers or prison guards.

Likewise here: 

The case of Kilmar Abrego García, an immigrant and longtime Maryland resident who the Trump administration admitted in court was sent in error to El Salvador, illustrates the threat. The Supreme Court ordered the administration to facilitate García’s return, but it has resisted taking action. Judge J. Harvie Wilkinson III — a Reagan appointee — warned in his Fourth Circuit order on April 17 that “the government is asserting a right to stash away residents of this country in foreign prisons without the semblance of due process that is the foundation of our constitutional order.”

The government’s claim that nothing can be done for García now that he’s out of U.S. custody, Wilkinson observed, “should be shocking not only to judges, but to the intuitive sense of liberty that Americans far removed from courthouses still hold dear.” 

That's surprisingly irrelevant to the case of Trump doing the same thing to American citizens. The reason they have no authority to do anything about Garcia is that he is a Salvadoran citizen, in El Salvador, under the control of his own lawful government. An American citizen abroad continues to enjoy US protection (and, in fairness to Trump, he has been pretty energetic about getting US citizens out of foreign prisons during his tenure). Whereas the US has no lawful power to demand El Salvador do much of anything for its own citizens, the US has a keen interest in protecting American citizens abroad.

I would like to believe that this is forbidden by the Constitution and specifically by the 8th Amendment, but this is not a good set of arguments for that being the case. I think the conditions in CECOT plainly violate the 8th Amendment, and that it shouldn't be legal to send Americans there under any circumstances. I wouldn't want to send them even to a nicer and more humane prison in El Salvador (or anywhere else).