The National Emergencies Act (Pub.L. 94–412, 90 Stat. 1255, enacted September 14, 1976, codified at 50 U.S.C. § 1601-1651) is a United States federal law passed to stop open-ended states of national emergency and formalize the power of Congress to provide certain checks and balances on the emergency powers of the President. The Act of Congress imposes certain procedural formalities on the President when invoking such powers. The perceived need for the law arose from the scope and number of laws granting special powers to the executive in times of national emergency.
The H.R. 3884 legislation was passed by the 94th United States Congress and signed by the 38th President of the United States Gerald R. Ford on September 14, 1976.
On 6 March 2014, U.S. President Barack Obama, invoked, inter alia, the National Emergencies Act, and signed an executive order that declared a national emergency and ordered sanctions, including travel bans and the freezing of U.S. asset, against not-yet-specified individuals, later to be determined by the Secretary of the Treasury (in consultation with the Secretary of State) who had "asserted governmental authority in the Crimean region without the authorization of the Government of Ukraine" and whose actions were found, inter alia, to "undermine democratic processes and institutions in Ukraine".
This summary is from Wikipedia.
The summary below was written by the Congressional Research Service, which is a nonpartisan division of the Library of Congress.
8/26/1976--Reported to Senate amended.
(Reported to Senate from the Committee on Government Operations with amendment, S. Rept. 94-1168) National Emergencies Act - =Title I: Terminating Existing Declared Emergencies= - States that all powers and authorities conferred by law upon the President, any other officer or employee of the Federal Government, or any department, agency, independent establishment, or any other body of the Federal Government, and all powers and authorities conferred by any Executive Order pursuant to law as a result of the existence of any national emergency in effect on the date of enactment of this Act are terminated two years from the date of such enactment. Defines such emergency as a general declaration of emergency made by the President. =Title II: Declarations of Future National Emergencies= - States that, with respect to Acts of Congress authorizing the exercise of any special or extraordinary power during a national emergency, the President is authorized to declare such national emergency. Provides that any national emergency declared by the President in accordance with this title shall terminate if (1) Congress terminates the emergency by concurrent resolution; or (2) the President issues a proclamation terminating the emergency. Requires that, not later than six months after a national emergency is declared, and not later than the end of each six-month period thereafter during which such emergency continues, each House of Congress shall meet to consider a vote on a concurrent resolution to determine whether that emergency shall be terminated. =Title III: Exercise of Emergency Powers and Authorities= - States that when the President declares a national emergency, no powers made available by statute for use in the event of an emergency shall become operative unless and until the President specifies the specific provisions of law under which he proposes that he, or other officers will act. =Title IV: Accountability and Reporting Requirements of the President= - Provides that when the President declares a national emergency, or Congress declares war, the President shall be responsible for maintaining a file, and an index thereof, of all significant orders issued by the President. Directs the President to transmit to Congress within 90 days after the end of each six-month period after such declaration, a report on the total expenditures incurred by the United States Government during such six-month period which are directly attributable to the exercise of powers and authorities conferred by such declaration. Requires that, not later than 90 days after the termination of each such emergency or war, the President shall transmit a final report on all such expenditures. =Title V: Repeal and Continuation of Certain Emergency Power and Other Statutes= - Repeals that provision of the Immigration and Nationality Act which stipulates that a native born or naturalized citizen of the United States shall lose his nationality for departing from or remaining outside of the jurisdiction of the United States in time of war or during a period declared by the President to be a period of national emergency for the purpose of evading or avoiding training and service in the military, air, or naval forces of the United States. Repeals the requirement that leases on specified property under the control of a military department must permit the Secretary of that department to revoke the lease at any time. Repeals specified regulations of consumer credit. Repeals that provision of the Tennessee Valley Authority Act of 1933, as amended, prohibiting the Tennessee Valley Authority from selling products except ferrophosphorus for use outside of the United States. Repeals that provision of the criminal code which makes it a crime to enter, remain in, leave, or commit any act in any military area contrary to restrictions applicable thereto which have been prescribed under the authority of an Executive Order of the President or designated military officer. Repeals the designated provisions of law regarding the promotion of commissioned officers of the Public Health Service. Repeals designated provisions of the Merchant Ship Sales Act of 1946 regarding price adjustments on the sale of surplus war-built vessels to United States citizens. Exempts designated provisions of law from this Act.