* They can grab anyone off the street and send them to a labor camp in a foreign country even if they have no connection to that country.
* If you want to challenge them in court, you have to do it in the location where the person is being held. They don't have to tell you where that is, and they can move the person to a venue where the courts will be favorable to them. They are moving people thousands of miles to Louisiana or Texas as quickly as possible.
* If they can get you out of the country before you can get into court to challenge them, too bad. The courts can do nothing to get you back, and the government certainly isn't going to try.
* You cannot challenge their decision that a gang or criminal organization constitutes an invasion by a foreign country, no matter how absurd it may be.
* You might be able to challenge whether the person is a member of that organization (originally they said you couldn't but they may be wavering on this point), but they are going to do everything they can to get you out of the country before you can get into court to challenge them.
* They don't have to tell the courts even the most basic publicly available information, like when flights departed.
As a practical matter, there is very little stopping them from grabbing anyone, even an American citizen, and sending them to a labor camp in El Salvador. Is it illegal? Sure - but they are making it almost impossible to get restitution in court.