A federal court has made a limited ruling against the NSA's mass collection of phone records. In a filing posted today, the Second Circuit Court of Appeals writes that the phone records program "exceeds the scope of what Congress has authorized," overturning a decision from 2013.

The American Civil Liberties Union brought its case against Director of National Intelligence James Clapper after Edward Snowden revealed that a government surveillance program was collecting metadata — including time stamps, phone numbers, and durations of calls — for millions of phone numbers. The NSA justified the program under Section 215 of the Patriot Act, which allows the government to collect "tangible things" relevant to a national security investigation. A federal judge originally said that the ACLU couldn't establish it had been harmed by this collection, but the three-member appeals court disagrees.

"The sheer volume of information sought is staggering." "It is not disputed that the government collected telephone metadata associated with the appellants’ telephone calls," writes circuit judge Gerard Lynch. Whether or not the government searches through this information — which it's said the ACLU can't prove — it could still potentially be a violation of the group's Fourth Amendment protections against "searches and seizures." Knowing the information was being collected could also have a chilling effect on freedom of speech, violating the First Amendment. This doesn't mean it's ruled the program unconstitutional; in fact, it explicitly says it's not dealing with that issue. But it calls the problem "sufficiently daunting" that Congress should address it, and it's not disputing the ACLU's grounds to sue over the possibility.

The court took issue with the program's secrecy — it's reviewed only internally, by a court whose decisions are secret — and with the administration's claim that Congress didn't intend to let its targets bring complaints. If a huge number of lawsuits could disrupt national security operations, it's only because of "the existence of orders authorizing the collection of data from millions of people," the ruling says. And it brings up one of the biggest criticisms of the program: that it's too vague and sweeping to be justified by Section 215. "Such an expansive concept of 'relevance' is unprecedented and unwarranted," writes Lynch. "The sheer volume of information sought is staggering."

Section 215 is already expiring next month Where Judge William Pauley III started his ruling with a warning about terrorism after the "bold jujitsu" of 9/11, this ruling is critical of the ongoing, expansive fight against it. "The government effectively argues that there is only one enormous 'anti‐terrorism' investigation, and that any records that might ever be of use in developing any aspect of that investigation are relevant to the overall counterterrorism effort," writes Lynch. He warns that this is a tortured reading of Section 215's limits. leaning too heavily on the fact that Congress hasn't explicitly cracked down on the NSA's activity. (Some members of the House of Representatives say they weren't even made aware of the program.) Its interpretation would require a "drastic expansion" of the intended scope of Section 215 and similar rules.

The ACLU has asked for a ruling that would stop the NSA from collecting information, at least until the issue was finally decided. But Section 215 is expiring next month, and Lynch writes that whatever Congress decides to do could "profoundly alter the legal landscape." If it's reauthorized, lower courts will have to go over the legal issues with the new rules. But at a pivotal moment in the surveillance debate, it's a strike against the phone surveillance program as it exists today.