It's quite a twist of events. While some people, notably immigrants and foreign visitors, are being kept out, some people apparently are (would be) getting kept in.

It's an unusual form of punishment. Not prison or money or community service, or ban from performing actions or duties, like with most crimes. No - you cannot leave the country. I can't think of any other crime for which this is the ultimate punishment (it can be a temporary one, but usually just to make sure people don't run away before a final judgment is made).

And I suppose for this to make any sense, this must apply only to actions that fall short of incitement to violence or terrorism - because for those you go to o prison. It must be things that, applied to not-Israel, are not crimes at all - else the law would be redundant. So I'm picturing something like, someone attensing a peaceful pro-Palestinian rally, and being told they cannot leave the country. Maybe even less, since people are already being prosecuted for that, with existing laws.

Most punishments involve some element of separating the perpetrator from the society. States pay money for prisons to keep criminals away, people are banned from professions where they screwed up. But here people are forced, at the expense of the US budget, to remain in the US among Americans.

It’s been used before to punish political speech, especially during the Mcarthy era against “un american” speech like support for labor rights where the government couldn’t win in court. I thought we had all agreed that was bad and moved passed it, but, I guess not.

(Notably it was used against WEB Du Boise and then when it was lifted and he traveled to Ghana, the US state department refused to renew his passport stranding him there until he became a Ghanaian citizen.)

Imagine if Nixon tried this during the Vietnam War.

Ofcourse America was still a functional democracy with the rule of law back then. His own party stabbed Nixon in the back when he got too crazy.

Most importantly no due process, no court judgement required. Just the discretion of Marco Rubio