The powers granted to the U.S. President are meant to be used in times of war or situations that threatens the security of the United States. Trump is using it nilly-willy for just about everything. It will, however, be difficult to come up with a law that would put a stop to this without harming the Executive Branch's effectiveness in a time of need.

But so far I'm pretty satisfied how Congress and the judiciary are putting reins on his powers. He recently threatened to halt all trade with Europe over Canada's associate EU membership. There's no way he can do that. Congress would step in.