The Obama administration intends to publicly reveal a secret memo outlining its legal justification for using drones to kill U.S. citizens it accuses of terrorism overseas, it emerged Tuesday.

An official told Al Jazeera that the Department of Justice has decided not to appeal a court order requiring disclosure of a redacted version of the document under the Freedom of Information Act.

The decision to release the document came a day before the Senate is to vote on advancing President Barack Obama's nomination of the memo's author, Harvard professor and former Justice Department official David Barron, to sit on the First U.S. Circuit Court of Appeals in Boston. Sen. Rand Paul, R-Ky., had vowed to attempt to block Barron's confirmation with a filibuster if the document was not made public. Paul issued a statement Tuesday saying he still opposes Barron's nomination.

Wednesday's expected vote would allow the Senate to move ahead with a final vote on Barron on Thursday. "I think we'll be OK," Senate Majority Leader Harry Reid, D-Nev., said earlier Tuesday.

Anwar al-Awlaki, an Al-Qaeda leader born in the United States, was killed after being targeted by a drone strike in Yemen in September 2011. Some legal scholars and human rights activists complained that it was illegal for the U.S. to kill American citizens away from the battlefield without a trial.

Senators, including those in Obama's own party, have called for the public release of the memo before the final confirmation vote. The White House agreed under pressure to show senators unredacted copies of all legal advice written by Barron regarding the potential use of lethal force against U.S. citizens in counterterrorism operations.

Until now, the administration has fought in court to keep the writings from public view. But an official told Al Jazeera that Solicitor General Donald Verrilli Jr. decided not to appeal an April 21 ruling requiring disclosure by the Second U.S. Circuit Court of Appeals in New York and that Attorney General Eric Holder concurred with his opinion.

The release could take some time, since the redactions are subject to court approval. And the administration is also insisting that a classified ruling on the case be redacted to protect information classified for national security, the official said.

The drone strike that killed Awlaki also killed another U.S. citizen, Samir Khan, also an Al-Qaeda member. Awlaki's 16-year-old son, Abdulrahman, was killed the following month in another drone attack.

The American Civil Liberties Union and two reporters for The New York Times, Charlie Savage and Scott Shane, filed a FOIA suit calling for the memo to be made public. In January 2013, U.S. District Court Judge Colleen McMahon ruled that she had no authority to order the document disclosed, although she chided the Obama administration for refusing to release it.

But a three-judge appeals court panel noted that after McMahon ruled, senior government officials spoke about the subject. The panel rejected the government's claim that the court could not consider official disclosures made after McMahon's ruling, including a 16-page Justice Department white paper on the subject and public comments by Obama in May in which he acknowledged his role in the Awlaki killing, saying he had "authorized the strike that took him out."

Al Jazeera and The Associated Press