I don't think they can countermand federal law, but there's no federal law that says ICE does have the right to not properly identify themselves.

In another thread i saw someone mention that this only applies to local law enforcement but that local law can ask the feds to follow it but they cant be forced to.

That is what i read too www.cbsnews.com/chicago/news...

They should offer the cops a bonus for each ice goon they get to remove their face coverings. Something to get them to be super annoying about it until ice either demasks or leaves.