The American Civil Liberties Union (ACLU) pressed ahead on Monday with a lawsuit to compel the CIA to turn over basic details about the US program of clandestine drone warfare, a week after startling contours of the program emerged in a new leak by an anonymous intelligence source.

The ACLU lawsuit seeks summary data from the CIA on drone strikes, including the locations and dates of strikes, the number of people killed and their identities or status. The ACLU also is seeking memos describing the legal reasoning underpinning the drone program.

None of the summary strike information is currently available to the public, which instead must rely on estimates compiled by analysts and journalists, based on reports on the ground.

“The case is really about the public’s right to know, the right of access to information about this very controversial set of policies,” said Jameel Jaffer, deputy legal director of the ACLU. “At this point the enemies of the United States already know that the CIA is carrying out drone strikes. The only effect of the kind of secrecy we’re seeing now is to keep Americans in the dark about their own government’s policies.”

The ACLU lawsuit pertains both to the CIA drone program and any information it may have on a parallel program operated by the defense department, Jaffer said.

In combination, the two programs are believed to have killed thousands of civilians in Pakistan, Yemen, Somalia and Afghanistan. Analysis based on classified documents provided by an unidentified whistleblower to the Intercept and published last week revealed that the military labels unknown people it kills as “enemies killed in action”.

The ACLU case suffered a setback in June, when a judge with the US district court for the District of Columbia ruled in favor of the CIA’s effort to keep the drone strike information and legal reasoning secret.

On Monday, the ACLU appealed that ruling to the DC circuit appeals court, which has previously ruled in favor of the ACLU in the case. In 2013, a three-judge panel on the court rejected a CIA contention that national security concerns prevented the agency from confirming or denying the possession of any pertinent records.

The ACLU has had partial success with similar freedom of information act lawsuits in the past. In 2009, the group won the release of four secret memos laying out the legal justifications for the CIA’s post-9/11 torture program.

“We are seeking [the drone memos] for precisely the same reasons we sought the torture memos,” Jaffer said. “They are the basis for the government’s most significant national security policy right now.

“We think that the public has a right to know both what the government’s purported legal justifications are for the drone strikes, and also of any limits that the government recognizes on its authority to carry out these kinds of strikes.”

The ACLU also is party, with the New York Times, to a second major drones transparency case currently working its way through the second US circuit court of appeals in Manhattan.

That case resulted in the release last year of a Justice Department memorandum describing an ability to kill an American citizen without trial in Yemen.

That memo contended that the protection of US citizenship was effectively removed by the 2001 Authorization to Use Military Force (AUMF), which blessed a global war against al-Qaida.

The memo was thought to provide the legal basis for the killing of Anwar al-Awlaki, the former al-Qaida propagandist and US citizen, in 2011.

In a post on the Just Security blog, Jaffer decried government noncompliance with freedom of information act (FOIA) requests.

“In practice... the government routinely withholds information that the FOIA requires it to disclose,” Jaffer wrote. “On the rare occasion when courts enforce the FOIA over the government’s objections, the government often manages to delay release of information by months or years, and the public gets access to information only long after it most needs it.”