The American Civil Liberties Union is suing the US government in an effort to compel a court to release documents detailing the Obama administration’s use of a secret, so-called “kill list” containing potential drone strike targets.

Filed Monday in US District Court in Manhattan, the lawsuit asks the Southern District of New York to order four government agencies, including the Departments of Justice, Defense and State, to heed Freedom of Information Act requests filed by the ACLU in 2013 concerning the administration’s “targeted killing” program.

Although the US has relied on unmanned weaponized aircraft, or drones, to conduct strikes in counterterrorism and military operations for over a decade, the ACLU says the Obama administration has been far from forthcoming when it comes to releasing details on to how those operations are carried out.

“Despite the public promises of openness, the government has continued to fight tooth-and-nail against releasing documents,” ACLU legal fellow Matthew Spurlock said in a statement Monday.

The ACLU began filing requests in October 2013 for records containing any legal justification for the lethal drone strikes and the process by which those targets are designated, “before-the-fact assessments” concerning potential civilian or bystander casualties and the names and numbers of individuals killed or hurt as a result of these “targeted killings.” Nearly a year and a half later, however, the ACLU says that none of the agencies served with FOIA requests have followed through and released documents, despite assurances given by Obama.

This week’s lawsuit asks the District Court to order the Justice Department, the Pentagon, the State Dept. and the CIA – as well as the Dept. of Defense’s Office of Legal Counsel and Office of Information Policy – to “immediately produce all records” on the drone strikes.

“The Obama administration has made numerous promises of greater transparency and oversight on drones,” Spurlock said. “In his 2013 State of the Union address, President Obama pledged to make lethal targeting ‘more transparent to the American people and the world’ because ‘in our democracy, no one should just take my word for it that we're doing things the right way.’ But the administration has failed to follow through on these commitments to openness, and it is continuing to withhold basic information.”

Jameel Jaffer, the ACLU’s legal director, told The Guardian this week that US-led drone strikes have been blamed in the deaths of thousands of people, including hundreds of innocent civilians.

“The public should know who the government is killing, and why it’s killing them,” Jaffer said.

Spurlock said Monday that the release of the Al-Awlaki memo was an “important victory for transparency,” but nevertheless leaves many questions unanswered.

A New York Times report from 2012 revealed that the Obama administration maintains an expanding “kill list,” described by the paper as “macabre ‘baseball cards’ of an unconventional war” containing the details of suspects sought for execution by drone.

One of the administration documents sought by the ACLU, and successfully received, revealed that the US considered Al-Awlaki an “operational leader” of an “enemy force,” and therefore could be targeted “as part of the US’ ongoing non-international armed conflict with Al-Qaeda.” With other requests for details having gone unfulfilled, however, the organization hopes to have a District Court judge compel the government to make further disclosures.

Explaining the 2011 strike that killed Al-Awlaki in Yemen, US Attorney General Eric Holder said in 2012 that “Al-Awlaki repeatedly made clear his intent to attack US persons and his hope that these attacks would take American lives.” He added: “Based on this information, high-level US government officials appropriately concluded that Al-Awlaki posed a continuing and imminent threat of violent attack against the United States.”

Spurlock said that the Obama administration’s drone program “lives far too deep in the shadows.” He added: “As long as the government continues its campaign of secret, unacknowledged lethal strikes across the globe, we will fight to subject this policy to the scrutiny and debate it deserves.”