The Obama administration has agreed to a review that could lead to the declassification of key surveillance orders in response to a lawsuit brought by Yahoo, potentially providing one of clearest views yet into the legal mechanics of the National Security Agency.

As required by judge Reggie Walton of the secret Fisa court, which oversees surveillance orders, the Justice Department will complete a declassification review of binding surveillance orders on Yahoo by 12 September, potentially setting the stage for their public release.

The key document at issue, an opinion from the court from 25 April 2008, mandating Yahoo's compliance with a bulk surveillance order, will have a declassification review completed in 45 days, the Justice Department told the court in a brief letter released Tuesday morning.

An additional declassification review of "briefs and materials" related to the April 2008 ruling will be complete "by Friday, September 27, 2013, 60 days from today," acting assistant attorney general for national security John Carlin told Walton in the letter, with "the other briefs and materials that the Government has identified as potentially relevant to the court's memorandum of opinion (see appendix A) on a rolling basis thereafter."

It is possible the Justice Department review will not result in the declassification of the documents. If not, however, it risks the ire of a key surveillance partner, the presiding judge of the surveillance court, and powerful legislators who urge transparency.

In a separate letter to senator Patrick Leahy, a Democrat from Vermont and the chairman of the Senate judiciary committee, Walton revealed that Yahoo was the only recipient of a bulk-surveillance order to plead its case before the Fisa court, after it refused to comply with a surveillance order in 2007 – prompting the court the following year to issue the order that Yahoo wishes to have declassified.

"There has been one instance in which the court heard arguments from a non-governmental party that sought to substantively contest a directive from the government," Walton wrote to Leahy in a letter dated 29 July.

"Yahoo refused to comply with the directives, and the government filed a motion with this court to compel compliance," Walton continued. "The court ordered and received briefing from both parties, and rendered a decision in April 2008."

It is unclear from the timetable what specifically the government will release, and how substantive it will be. Obama administration lawyers have recently said in speeches and congressional testimony that declassifying Fisa court orders is difficult since they frequently contain references to classified material. But owing to a swell of public and congressional outrage over the bulk surveillance programs, a consensus has emerged inside the government that greater transparency around the efforts is needed to forestall their cancellation.

The Justice Department and office of the director of national intelligence did not respond to a request for comment.

On Wednesday, Leahy, the powerful judiciary committee chairman in the Senate, will hold the committee's first hearing on the bulk surveillance since the Guardian and the Washington Post disclosed it last month, thanks to whistleblower Edward Snowden. Leahy is sponsoring a bill to shorten the lifespan of the Patriot Act and end surveillance in bulk as well as a separate effort to force greater transparency around key Fisa court rulings.

Only rarely does the public see the orders issued by the secretive, 35-year-old court. But Yahoo, a partner in the NSA's collection of online communications believed to involve foreigners, prevailed upon the court to release a 2008 memorandum showing the tech giant "objected strenuously" to the government's requests for customer data.

Judge Walton, the presiding judge of the court, ruled in Yahoo's favor on 15 July. Yahoo's push to show that it was compelled to participate in the internet communications collection, a program known as Prism and justified under Section 702 of the Fisa Amendments Act of 2008, was part of a backlash by the NSA's corporate partners against the disclosure of their collaboration by whistleblower Edward Snowden in the Guardian and the Washington Post.

Yahoo is one of a number of Prism partners who argue that their participation in the NSA program, which collects the online habits of people believed to be non-Americans outside the United States, occurred under duress. Google and Microsoft are pressing the court to release more information about the circumstances under which they comply with the government's bulk surveillance orders. Other major tech firms have also called for additional transparency around government surveillance requests.

Assuaging the telecommunications and internet firms it relies upon for surveillance is important for the NSA. Accordingly, the government took "no position" objecting to Yahoo's disclosure request when it responded to the request on 25 June.

Congressional critics of the bulk surveillance efforts charge that the secret court, which rarely rejects government surveillance requests, has allowed the government to effectively rewrite the laws outside of public and often congressional view.

"Because the Fisa court's rulings are secret, most Americans had no idea that the court was prepared to issue incredibly broad rulings, permitting the massive surveillance that finally made headlines last month," Senator Ron Wyden, an Oregon Democrat, said in a speech last week.

"The secret rulings of the foreign intelligence surveillance court have interpreted the Patriot Act, as well as section 702 of the Fisa statute, in some surprising ways, and these rulings are kept entirely secret from the public. These rulings can be astoundingly broad. The one that authorizes the bulk collection of phone records is as broad as any I have ever seen."

In addition to the chorus of voices urging the Fisa court to declassify the bulk collection orders, congressman Adam Schiff (Democrat, California), a member of the House intelligence committee, is pushing legislation that would transform the court into an adversarial body for the first time in its history, with a lawyer appointed to argue for the public's privacy interests. Schiff also advocates making the court's members presidential appointees confirmed by the Senate instead of federal judges selected by the chief justice of the US supreme court.

Walton wrote to Leahy that the recipients of Fisa court orders for phone or internet records "provide multiple opportunities" for those companies to challenge the surveillance. Yet outside of Yahoo's unprecedented 2007 challenge, the only times a lawyer not representing the government have appeared before the Fisa court have not had to do with a direct effort to resist the records collection.

"[T]here have been several instances – particularly in the last several months – in which nongovernmental parties have appeared before the court outside the context of a challenge to an individual court order or a government directive," Walton wrote.

Those parties have included the ACLU, the Electronic Frontier Foundation, Google and Microsoft, mostly inquiring about additional disclosures from the court "To date, no electronic communication provider has opted to challenge a directive issued pursuant to Section 702," as Yahoo's objection in 2007 was to the statutory precursor of Section 702.

• This article was updated on 30 July 2013. The first line originally stated unequivocally that the Yahoo documents would be declassified. This has been edited for clarity. Further context was also added.