A lot of lawyers and humanitarian law workers will have to think hard about whether it is safe to set foot in the US. This includes people working in conflict resolution organizations. Advising prescribed armed groups, for example, that it is a good idea not to lay anti-personnel landmines (something the USA incidentally still does not wish to ban), is now a crime.
(By the way: humanitarian law = law of armed conflict.)
In "Holder vs. Humanitarian Law Project" (21 June 2010), the US Supreme Court concluded that giving legal advice to groups proscribed by the US government as "terrorist organizations" is to be construed as 'material support', and hence a crime (18 U. S. C. §2339B(a)(1)), punishable by up to a life-term in jail. The prosecutions have not started yet, but that is no guarantee that you won't be the first.
What can I say to that? Well, actually, the hypocricy of the system leaves me almost speechless. Once again I turn to Job's rhetorical questions:
"Shall one who hates justice govern? Will you condemn one who is righteous and mighty, who says to a king, 'You scoundrel!' and to princes, 'You wicked men!'; who shows no partiality to nobles, nor regards the rich more than the poor, for they are all the work of his hands?" (Job 34:17-19)
Well, one might say to brother Job, it must be said that in many places, including the USA, those who hate justice do indeed govern. They do have lots of company in other places, but that's no excuse.