The laws that created ICE did not say it was to be used as the president’s personal Gestapo to disappear any non-citizen who says something he disagrees with. They assume the people directing ICE can be trusted not to abuse the power they have. As there is no explicit written law saying you can’t do what trump is doing, he did that.
Fortunately for all Americans there is an explicit unambiguous bill of rights. If there wasn’t do you really think Trump would not have found a prosecutor and 11 jurors who think saying “MAGATs” or “Conservative evangelicals want trans people to die” counts as inciting hate?