Yahoo reports that it is on the verge of releasing 1,500 pages of documents related to a long court battle over its participation in the PRISM program, a National Security Agency program revealed last summer as part of the Snowden leaks.

A leaked top-secret slide about PRISM shows that Yahoo was one of the first participants, having begun contributing to the database in March of 2008. It did so under severe duress. Company executives believed the government's demand for data was "unconstitutional and overbroad" and fought it in court.

"Our challenge, and a later appeal in the case, did not succeed," explained Yahoo General Counsel Ron Bell in a blog post published today. "The Foreign Intelligence Surveillance Court (FISC)... ordered us to give the U.S. Government the user data it sought in the matter."

After it lost, Yahoo was threatened with $250,000 per day fines if it didn't comply with the program. Not only that, but the government got permission to share the ruling with other companies in order to put pressure on them as well, according to a just-published story by The Washington Post.

Ultimately, Microsoft, Google, Facebook, YouTube, Skype, AOL, and Apple would all participate in PRISM. Before it was discontinued in 2011, the program gathered up vast amounts of what the government called "metadata" about e-mail, including who users e-mailed and when.

The original order to Yahoo in 2007 required the company to provide information on targets that were outside the US, even if the person was a US citizen.

According to Bell's blog post, the "key takeaways" include:

An expanded version of the FISC-R opinion in the case, originally released in 2008 in a more redacted form.

The release of the never-before-seen 2008 FISC opinion that we challenged on appeal.

The parties’ briefs, including some of the lower court briefings in the appendices.

An Ex-Parte Appendix of classified filings.

A partially redacted certification filed with the FISC, as well as a mostly unredacted directive that Yahoo received.

Yahoo still hasn't posted the documents, and the FISA Review Court has no public docket. It says it will update the post with links to the documents as soon as they are available.

Update 9/15: The Center for Democracy and Technology is hosting these documents, and they are available here.