A three-judge panel in New Orleans temporarily blocked mifepristone from being sent in the mail.
The troop withdrawal could take up to a year, according to the Pentagon.
The 1973 War Powers Resolution states a president must end hostile U.S. military action within 60 days, unless Congress authorizes further action.

The Justice Department issued the subpoena last July, but the hospital had not complied.
As of March 31, the company’s individual exchange business had 369,000 members in individual and family plans.
‘The Chinese military has conducted research into cable‑cutting technologies,’ said Sen. Jim Risch.
It’s part of a series of actions by the Trump administration aiming to prevent illegal immigrants from obtaining taxpayer benefits or preferential treatment.
Updated regulations aim to enhance safety and oversight.
‘Our state government and political system are broken,’ the lawmaker said, adding that the best way to continue her fight is from outside the government.

No injuries were reported in connection to the product, which does not meet labeling requirements, federal officials said.
The release is structured as an ‘emergency exchange’ that oil companies must return later.
A federal lawsuit filed Thursday in the Middle District of Louisiana seeks to block state officials from suspending U.S. House primary elections.
TrumpIRA will enable low- and middle-income Americans to shop for retirement plans eligible for a federal matching contribution.
Rubio and China’s diplomat also discussed the Iran war and Taiwan, according to a readout.
The bill goes to Trump’s desk and will end a shutdown that began on Feb. 14.
Havana may be forced to the negotiation table to restore the island nation’s energy lifeline, following the U.S. capture of Venezuela’s Maduro.
U.S. troops have been in Germany continuously since 1945, when American forces occupied the country after World War II.
The president said the U.S. destroyed 80 percent of Iran’s missiles and missile factories and would take out the rest ‘very quickly if we don’t make a deal.’
The House also moved forward with the latest version of the Farm Bill.
Acting War Department Comptroller Jules Hurst said expended U.S. weapons accounted for most of the U.S. cost of the Iran conflict.