Monkeypox? Climate? Deciding what’s a national emergency

FILE - President Donald Trump speaks during a news conference about the coronavirus in the Rose Garden of the White House, Friday, March 13, 2020, in Washington. Trump declared COVID-19 a national emergency in 2020 and Biden has extended it through at least February 2023. (AP Photo/Evan Vucci, File)

FILE - President Nixon poses for a photo at his White House desk March 23, 1970 after making an appearance on nationwide television to announce that he has ordered the use of troops to move the strike-bound mail in New York City. Nixon issued a series of national emergencies, including on currency restrictions and a national postal strike. (AP Photo, File)

President Joe Biden speaks in the East Room of the White House in Washington on Tuesday. Climate activists are clamoring for President Joe Biden to declare a national climate emergency, calls the White House has so far not headed. (AP Photo/Susan Walsh, File)

WASHINGTON — In November 1979, a little over a week after student militants seized control of the U.S. Embassy in Tehran and took 52 American citizens hostage, President Jimmy Carter issued Executive Order 12170 declaring a national emergency against Iran.