From the press release on Sen. Merkley’s website (emphasis mine):

June 11, 2013

Washington, DC – Today, Oregon’s Senator Jeff Merkley and Senator Mike Lee (R-UT), accompanied by Senators Patrick Leahy (D-VT), Dean Heller (R-NV), Mark Begich (D-AK), Al Franken (D-MN), Jon Tester (D-MT), and Ron Wyden (D-OR), introduced a bill that would put an end to the “secret law” governing controversial government surveillance programs.  This bill would require the Attorney General to declassify significant Foreign Intelligence Surveillance Court (FISC) opinions, allowing Americans to know how broad of a legal authority the government is claiming to spy on Americans under the PATRIOT Act and Foreign Intelligence Surveillance Act…

The Foreign Intelligence Surveillance Court (FISC) is a special U.S. federal court tasked with authorizing requests for surveillance both inside and outside the United States. Because of the sensitive nature of these requests, the FISC is a “secret court.” The FISC rulings, orders, and other deliberations are highly classified.  The Court’s rulings can include substantive interpretations of the law that could be quite different from a plain reading of the law passed by Congress, and such interpretations determine the extent of the government’s surveillance authority. There is certainly information included in the Court’s orders and rulings that is necessarily classified, related to the sources and methods of collection used by intelligence agencies. However, the substantive legal interpretations of what the FISC says the law means should be made public.

This legislation would accommodate national security concerns. If the Attorney General determines that a Court opinion cannot be declassified without undermining national security interests, then the Attorney General can declassify a summary of the opinion. If the Attorney General determines that even a summary of an opinion would undermine national security, the Attorney General is required to provide a report to Congress describing the process to be implemented to declassify FISA Court opinions including an estimate of the number of opinions that will be declassified and the number that are expected to be withheld because of national security concerns…

See also this summary in The Hill for more information.   I learned of the bill from an editorial in yesterday’s NY Times, “Details on Spying, Not More Assurances”.