There were no less than 30 “national emergencies” in effect as of February 1, according to a tabulation prepared by the Congressional Research Service. An additional 21 national emergencies that are no longer in effect were also identified by CRS.
Under the National Emergencies Act, a declaration of national emergency can be used to activate presidential powers that would otherwise be unavailable....
See Declarations under the National Emergencies Act, Part 1: Declarations Currently in Effect, CRS Legal Sidebar, February 1, 2019; and Declarations under the National Emergencies Act, Part 2: Declarations No Longer in Effect, CRS Legal Sidebar, February 1, 2019.
Together, the two reports replicate (with some variations) a table prepared lately by the Brennan Center for Justice, which has researched national emergency powers.Justice Robert Jackson Concurring opinion, Youngstown v. Sawyer, 343 U.S. 579 (June 2, 1952)"
When the President takes measures incompatible with the expressed or implied will of Congress, his power is at its lowest ebb, for then he can rely only upon his own constitutional powers minus any constitutional powers of Congress over the matter. Courts can sustain exclusive presidential control in such a case only by disabling the Congress from acting upon the subject. [Footnote 4/4] Presidential claim to a power at once so conclusive and preclusive must be scrutinized with caution, for what is at stake is the equilibrium established by our constitutional system.