Is it true that a presidential declaration of emergency in the US can be overridden by simple majorities of both houses, i.e. the US House of Representatives and the US Senate?
In theory, yes. In practice, probably not. In theory, the President could agree with Congress that the emergency is over. In practice, the President would likely object the resolution and send it back to Congress with his veto. In that case, it would take a 2/3 majority in both houses to override the veto.
As originally written, the National Emergencies Act of 1976 explicitly allowed a simple majority in both houses of Congress to terminate a Presidential declaration of an emergency. From https://www.govtrack.us/congress/bills/94/hr3884/text (emphasis mine),
SEC. 202. (a) Any national emergency declared by the President in accordance with this title shall terminate if —
Congress terminates the emergency by concurrent resolution ; or
the President issues a proclamation terminating the
This simple majority override ran into a severe problem with Immigration and Naturalization Service v. Chadha, 462 U.S. 919 (1983), which addressed a case concerning a law that allowed a legislative veto by a single house of Congress. The 7-2 Supreme Court decision on that case very broadly ruled unconstitutional not just that particular law but also virtually all other attempts by Congress to thwart by legislative veto what is very explicitly in the Constitution. As a result, Congress in 1985 modified the termination procedures of the National Emergencies Act to read (emphasis mine)
§1622. National emergencies
(a) Termination methods
Any national emergency declared by the President in accordance with this subchapter shall terminate if—
- there is enacted into law a joint resolution terminating the emergency; or
- the President issues a proclamation terminating the emergency.
Concurrent resolutions are non-binding and are not subject to presidential veto. Joint resolutions on the other hand are subject to presidential veto.