The secret court that has been ordering telecoms like Verizon to give the NSA a fire hose of metadata was asked today to explain the legal rationale behind authorizing surveillance of this magnitude.

The Guardian was the benefactor of a whistleblower who provided it with a copy last week of the Foreign Intelligence Surveillance Court's recent and secret opinion requiring Verizon to provide the NSA with the phone numbers of both parties involved in all calls, the International Mobile Subscriber Identity (IMSI) number for mobile callers, calling card numbers used in the call, and the time and duration of the calls.

The applicable law is one of the most controversial provisions of the Patriot Act — Section 215. It allows the FISA court to authorize broad warrants for most any type of records, including those held by banks, doctors and phone companies. Lawmakers have repeatedly voted to prevent the act from expiring. The government only needs to show that the information pertains to an "authorized investigation." No connection to a terrorist or spy is required.

But was the law, officially called the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001, really meant to enable the government to conduct such massive spying?

That's what the American Civil Liberties Union and others want to know. They asked the FISA court today to release its secret opinions on the constitutionality of Section 215.

Because there is a longstanding American tradition of public access to judicial opinions; because such access positively contributes to the integrity of the judicial process, the democratic legitimacy of this Court, and the public understanding of laws passed in its name; and because the release of opinions interpreting Section 215 would illuminate crucial gaps in the public knowledge about the breadth of its government's surveillance activities under the statute, this Court should conclude that the public's First Amendment right of access attaches to the Court's legal opinions relating to Section 215. (.pdf)

The secret court came to life in the wake of the Watergate scandal under the President Richard M. Nixon administration. It approved all of the 1,856 government surveillance requests last year. Its opinion last week provided no legal analysis other than citing the Patriot Act.

But the court has, indeed, issued secret opinions about its legal rationale – opinions that some members of Congress were briefed on.

Two Democratic senators urged the Obama administration last year to declassify the secret court rulings that they said gave the government far wider domestic spying powers under the Patriot Act than intended.

U.S. Senator Ron Wyden (D-Oregon) and Sen. Mark Udall (D-Colorado) wrote Attorney General Eric Holder:

"We believe most Americans would be stunned to learn the details of how these secret court opinions have interpreted section 215 of the Patriot Act. As we see it, there is now a significant gap between what most Americans think the law allows and what the government secretly claims the law allows. This is a problem, because it is impossible to have an informed public debate about what the law should say when the public doesn’t know what its government thinks the law says."

Holder did not oblige.

Meanwhile, Edward Snowden, a former computer security administrator for the CIA and current contractor for the NSA, over the weekend outed himself as the source of a string of explosive documents, including the FISA Verizon order, describing NSA surveillance activities against U.S. citizens and foreign targets.

The 29-year-old, who now works for the defense contractor Booz Allen Hamilton on projects for the NSA in Hawaii, revealed himself as the source of documents provided to the Guardian and Washington Post about the NSA's collection of phone records belonging to millions of Americans as well as a surveillance program called PRISM that targets the internet communications and activities of foreign targets.