Court documents were released on Thursday, showing that the U.S. government threatened Yahoo with fines of $250,000 a day in 2008 if it didn’t comply with demands to provide communications from its users. The documents are very significant because they highlight how the government has made companies participate in the NSA’s infamous PRISM surveillance program.

Over 1,500 documents relating to Yahoo’s 2007-2008 challenge to the the expansion of U.S. surveillance laws, which were previously secret, were released.

In ’07, the government amended a law to demand user info from online services, and Yahoo refused to comply, viewing it as unconstitutional. Yahoo challenged (and appealed), but was unsuccessful.

“The Foreign Intelligence Surveillance Court (FISC) upheld the predecessor to Section 702 of the FISA Amendments Act. The Court ordered us to give the U.S. Government the user data it sought in the matter,” explains Yahoo General Counsel Ron Bell. “The FISC and the FISC-R are ‘secret’ courts that oversee requests by the U.S. Government for surveillance orders and other types of legal process in national security investigations. The Court’s hearings and records are closed to the public and typically classified. For example, our role in the 2007-2008 lawsuit remained classified until 2013. In spite of this, we fought to declassify and to share the findings from the case.”

“A decision to open FISC or FISC-R records to the public is extremely rare,” he adds. “Now that the FISC-R has agreed to unseal the proceedings at our request, we are working to make these documents available. (NOTE: There is no FISC-R public docket, so we are in the process of making the complete 1500 pages of information available. We will update this Tumblr with the link to those documents as soon as they are ready.)”

Yahoo lists the following as the key takeaways from the documents:

While there is a ton of new information about all of this available, there are still classified documents. Yahoo says it’s still pushing to have other materials released.

Image via Yahoo