TY, I agree the Framers gave each branch pretty broad latitude to do as it saw right, in whatever the exigencies. Certainly it is useful that the Executive can stretch his/her powers quite far when times demand. Then, emergency past, Congress and the courts can beat back the excesses. (Took Hamilton to see, some 20 years after ratification, that those perceived weaknesses/incompletenesses of the Constitution were in fact some of its greatest strengths.)
BUT. Do you really not think some of Obama's application of those principles goes too far? Due process, once we get used to its being lost, may be frightful hard to recover.