Many of the things Trump says he would do if elected are not within the limited powers we grant presidents. Presidents cannot unilaterally spend taxpayer money, cannot impose tariffs on foreign goods, and cannot dictate to corporations where they will invest. They also cannot expect soldiers to follow illegal orders, as Trump has said he would demand, from the use of torture — prohibited by our Constitution and the treaties that are the law of the land — to the killing of innocent civilians, notably the children of terrorists he describes as Islamic (terrorists whom I consider Muslim apostates who describe themselves in their own publications as apocalyptic believers expecting the word to end soon).
Businessmen can, as Trump often does, dismiss people and move on. Presidents do not enjoy that luxury. They must contend with ever-present forces that are not subject to their control. A president cannot dismiss a troublemaking foreign head of state, cannot order Congress to pass laws, and cannot disobey the rulings of judges — not if we are to be a free people, living subject to the rule of law that protects our individual liberties. Yet Trump makes clear that he would do all these things. His vision is, in many ways, not that of a president but of a dictator, as many others have observed in both political parties and beyond America’s borders.
—David Cay Johnston
The Making of Donald Trump