NEW YORK — The secret US government memo outlining the justification for the use of drones to kill American terror suspects abroad was released by court order Monday, yielding the most detailed inside look yet at the legal underpinnings of the Obama administration’s program of ‘‘targeted killings.’’
The 41-page memo — whose contents had previously been summarized and released piecemeal — was heavily redacted for national security reasons, with several entire pages and other passages whited out.
But it argues among other things that a targeted killing of a US citizen is permissible under a 2001 law passed by Congress soon after 9/11. That law empowered the president to use force against organizations that planned and committed the attacks.
‘‘The release of the memo will allow the public to better assess the lawfulness of the government’s targeted killing policy and the implications of that policy,’’ said Jameel Jaffer, an American Civil Liberties Union attorney who argued for release of the memo. ‘‘Despite the release of this memo, the public still knows scandalously little about who the government is killing and why.’’
He said the memo contains the first formal acknowledgment by the government that the CIA is involved in the program.
The July 10 memo was written by David Barron, who at the time was acting chief of the Justice Department’s Office of Legal Counsel. A Harvard Law professor, Barron was recently confirmed as a judge in the First US Circuit Court of Appeals in Boston.
It was released after a yearlong legal battle by The New York Times and the ACLU.
The memo specifically provided the legal justification for the September 2011 killing in Yemen of Anwar al-Awlaki, an Al Qaeda leader and one-time cleric at a Virginia mosque who had been born in the United States, and another US citizen, Samir Khan, who edited Al Qaeda’s Internet magazine. An October 2011 strike also killed Abdulrahman al-Awlaki, the cleric’s teenage son and also a US citizen.
Awlaki had been involved in an abortive attack against the United States and was planning other attacks from his base in Yemen, the memo said.
It said the authority to use lethal force abroad may apply in certain circumstances to a US citizen who is part of the forces of an enemy organization.
The memo said the Defense Department operation was being carried out against someone who was within the core of individuals against whom Congress had authorized the use of ‘‘necessary and appropriate’’ force.
The Second US Circuit Court of Appeals in New York released the memo after the Times and the ACLU sued for any documents in which Justice Department lawyers had discussed the highly classified ‘‘targeted killing’’ program.
The appeals court ordered the memo disclosed after noting that President Obama and other senior government officials had commented publicly on the subject.
David E. McCraw, vice president and assistant general counsel for the Times, called the memo ‘‘a critical addition to the public debate over targeted killings and should fuel a richer discussion of the legal and security issues that are at the heart of that debate.’’
White House spokesman Josh Earnest, responding to criticism from groups that complained it took a court order to get the memo released, said the administration worked through the legal system ‘‘to produce a redacted document that protected national security interests while at the same time trying to live up to our commitment to transparency.’’
‘‘In this case, I think even the groups that sharply criticized us would call this a win for transparency,’’ Earnest said.
US officials considered Awlaki to be an inspirational leader of Al Qaeda, and they have linked him to the planning and execution of several attacks targeting American and Western interests, including a 2009 attempt on Christmas Day to blow up a Detroit-bound airliner.
Pardiss Kebriaei, a senior attorney with the Center for Constitutional Rights, said the memo’s contents showed that the targeted killing program was built on ‘‘gross distortions of law.’’
Kebriaei, who worked with the ACLU on two lawsuits challenging Awlaki’s killing, estimated that more than 4,000 people may have been killed by drone strikes since 2009.