> The 1st (because the actual basis was often protected speech unrelated to the asserted premise of removal)

This sounds like you are talking about the students who were detained and deported. Were any of them sent to El Salvador? My understanding is that they had their student visas revoked on the basis of 8 USC 1182(a)(3)(C)(i):

> An alien whose presence or activities in the United States the Secretary of State has reasonable ground to believe would have potentially serious adverse foreign policy consequences for the United States is deportable.

I don't know the specifics of the cases pertaining to the students, but from a plain reading this doesn't seem altogether unreasonable. I think it's obvious that this is being done at the behest of Israel, but it doesn't seem explicitly illegal.

> 5th (because of denial of due process) [...] 8th (because of conditions in the prison where they are sent) [...] and 13th (because the prison involves involuntary servitude, and they were condemned to it without a criminal conviction)

I couldn't find clarification as to what section of the prison the deportees are being held in. I understand that the prison is set up such that lower-level offenders are required to work or study almost every waking hour of the day, whereas gang members are segregated and not permitted to leave their cells at all. The key issue here seems to be due process, which is in turn dependent on a court ruling on the application of the Alien Sedition acts being improper.