“The public has a right to know the full scope of Russian interference in the 2016 United States presidential election and whether the president of the United States played any role in such interference,” EPIC said in the lawsuit. “The public also has a right to know whether the president unlawfully obstructed any investigation into Russian election interference or related matters. The requested records are vital to the public's understanding of these issues and to the integrity of the political system of the United States.”

EPIC's public records request sought documents in over a dozen categories, including Mueller's final report to the attorney general, and any drafts and exhibits related to the report.

It also sought access to reports, and related drafts and exhibits concerning the “status of the investigation,” records that were prepared to notify Congress of developments in the probe, and records and recommendations that were prepared for lawmakers' “eventual consideration.” The request also sought access to records related to possible Justice Department referrals for “administrative remedies, civil sanctions or other governmental action outside the criminal justice system.”

Barr said Friday in a letter to U.S. Senate and House leaders that he was reviewing Mueller's report and “may be in a position to advise you of the special counsel's principal conclusions as soon as this weekend.”

Barr also said he would meet with Deputy Attorney General Rod Rosenstein and Mueller to determine what “other information from the report can be released to Congress and the public consistent with the law, including the special counsel regulations and the department's long-standing practices and policies.”

“I remain committed to as much transparency as possible, and I will keep you informed as to the status of my review,” Barr wrote.

The Justice Department, Barr added, had not prevented Mueller from taking any action.

John Davisson, counsel for EPIC, said Friday the public had a right to know the full scope of Mueller's investigation. “It is essential that the complete special counsel report be released. EPIC's Freedom of Information Act case will ensure that happens,” he said.

Congressman Jerrod Nadler, D-New York, chairs a House Judiciary Committee meeting. Credit: Diego M. Radzinschi /ALM

The lawsuit came as Democratic lawmakers made their own calls for transparency, demanding that Mueller's report to Barr be shared with Congress.

“Give it all to Congress. Make it public,” tweeted Sen. Chris Murphy, D-Connecticut. “Err on the side of transparency. The future of American democracy depends on it.”

In the House, Judiciary Committee Chairman Jerrold Nadler said, “We look forward to getting the full Mueller report and related materials.”

“Transparency and the public interest demand nothing less,” he added. “The need for public faith in the rule of law must be the priority.”

Read the complaint below: