What the President Could Do If He Declares a State of Emergency (The Atlantic, more at the link):

It would be nice to think that America is protected from the worst excesses of Trump’s impulses by its democratic laws and institutions. After all, Trump can do only so much without bumping up against the limits set by the Constitution and Congress and enforced by the courts. Those who see Trump as a threat to democracy comfort themselves with the belief that these limits will hold him in check.

But will they? Unknown to most Americans, a parallel legal regime allows the president to sidestep many of the constraints that normally apply. The moment the president declares a “national emergency”—a decision that is entirely within his discretion—more than 100 special provisions become available to him. While many of these tee up reasonable responses to genuine emergencies, some appear dangerously suited to a leader bent on amassing or retaining power. For instance, the president can, with the flick of his pen, activate laws allowing him to shut down many kinds of electronic communications inside the United States or freeze Americans’ bank accounts. Other powers are available even without a declaration of emergency, including laws that allow the president to deploy troops inside the country to subdue domestic unrest.