In a ruling certain to profoundly shape the ongoing debate over surveillance reform in Congress, the U.S. Court of Appeals for the Second Circuit today held that the National Security Agency’s indiscriminate collection of Americans’ telephone calling records exceeds the legal authority granted by the Patriot Act’s controversial section 215, which is set to expire at the end of this month. Legislation to reform and constrain that authority, the USA Freedom Act, has drawn broad bipartisan support, but Senate Majority Leader Mitch McConnell has stubbornly pressed ahead with a bill to reauthorize §215 without any changes. But the Second Circuit ruling gives even defenders of the NSA program powerful reasons to support reform.

McConnell and other reform opponents have consistently insisted, in defiance of overwhelming evidence, that the NSA program is an essential tool in the fight against terrorism, and that any reform would hinder efforts to keep Americans safe—a claim rejected even by the leaders of the intelligence community. (Talk about being more Catholic than the Pope!) Now, however, a federal appellate court has clearly said that no amount of contortion can stretch the language of §215 into a justification for NSA’s massive database—which means it’s no longer clear that a simple reauthorization would preserve the program. Ironically, if McConnell is determined to salvage some version of this ineffective program, his best hope may now be… the USA Freedom Act!

The Freedom Act would, in line with the Second Circuit opinion, bar the use of §215 and related authorities to indiscriminately collect records in bulk, requiring that a “specific selection term,” like a phone number, be used to identify the records sought by the government. It also, however, creates a separate streamlined process that would allow call records databases already retained by telephone companies to be rapidly searched and cross-referenced, allowing NSA to more quickly obtain the specific information it seeks about terror suspects and their associates without placing everyone’s phone records in the government’s hands. If the Second Circuit’s ruling is upheld, NSA will likely have to cease bulk collection even if Congress does reauthorize §215. That makes passage of the Freedom Act the best way to guarantee preservation of the rapid search capability McConnell seems to think is so important—though, of course, the government will retain the ability to obtain specific phone records (albeit less quickly) under either scenario. With this ruling, in short, the arguments against reform have gone from feeble to completely unsustainable.

A few notable points from the ruling itself. Echoing the reasoning of the Privacy and Civil Liberties Oversight Board’s extremely thorough report on §215, the Second Circuit rejected the tortured legal logic underpinning both the NSA telephone program and a now-defunct program that gathered international Internet metadata in bulk. The government had persuaded the Foreign Intelligence Surveillance Court to interpret an authority to get records “relevant to an authorized investigation” as permitting collection of entire vast databases of information, the overwhelming majority of which are clearly not relevant to any investigation, on the premise that this allows NSA to later search for specific records that are relevant. As the court noted, this not only defies common sense, but it is wildly inconsistent with the way the standard of “relevance”—which governs subpoenas and court orders used in routine criminal investigations— has been interpreted for decades. If every American’s phone records are “relevant” to counterterrorism investigations, after all, why wouldn’t those and other records be similarly “relevant” to investigations aiming to ferret out narcotics traffickers or fraudsters or tax cheats? Past cases invoked by the government, in which courts have blessed relatively broad subpoenas under a standard of “relevance” only underscore how unprecedented the NSA’s interpretation of that standard truly is—since even the broadest such subpoenas fall dramatically short of the indiscriminate, indefinite hoovering the agency is now engaged in.

The court also quickly dispatched arguments that the plaintiffs here lacked standing to challenge the NSA program. In general, parties seeking to challenge government action must demonstrate they’ve been harmed in some concrete way—which presents a significant hurdle when the government operates behind a thick veil of secrecy. Since documents disclosed to press by Edward Snowden—and the government’s own subsequent admissions—leave little question that the plaintiffs’ phone records are indeed being obtained, however, there’s no need for a further showing that those records were subsequently reviewed or used against the plaintiffs. That’s critical because advocates of broad surveillance powers have often sought to argue that the mere collection of information, even on a massive scale, does not raise privacy concerns—and focus should instead be on whether the information is used appropriately. The court here makes plain that the unauthorized collection of data—placing it in the control and discretion of the government—is itself a privacy harm.

Finally, the court repudiated the Foreign Intelligence Surveillance Court’s strained use of the doctrine of legislative ratification to bless the NSA program. Under this theory—reasonable enough in most cases—when courts have interpreted some statutory language in a particular way, legislatures are presumed to incorporate that interpretation when they use similar language in subsequent laws. The FISC reasoned that Congress had therefore effectively “ratified” the NSA telephone program, and the sweeping legal theory behind it, by repeatedly reauthorizing §215. But as the court pointed out—somewhat more diplomatically—it’s absurd to apply that doctrine to surveillance programs and legal interpretations that were, until recently, secret even from many (if not most) members of Congress, let alone the general public.

While the court didn’t reach the crucial question of whether the program violates the Fourth Amendment, the ruling gives civil libertarians good reason to hope that a massive and egregious violation of every American’s privacy will finally come to an end.