Steph...I agree POTUS action may be  constitutional but it does not mean the action is necessarily  legal.   POTUS may do something he is allowed to do under the constitution but  the action may be forbidden under another federal statute or even a treaty.  Case in point, throughout the campaign POTUS kept referring to the travel ban from Muslim countries.  We have got to ask ourselves the question, Is Muslim a nationality or a religion.  This is why if and when this comes before Scotus , along with other issues , they will decide.