Many others have already weighed in about the significance of last week’s ruling in ACLU v. Clapper. Here are my own quick thoughts. As regular readers of this blog already know, I’m counsel to the plaintiffs in the litigation.

1. The ruling is a major victory for the many advocates from across the political spectrum, outside the government and inside, who have been arguing that some of the government’s surveillance activities are overbroad and unlawful and that the system of oversight that Congress established in 1978 isn’t working. The FISA court signed off on the call records program dozens of times after hearing argument only from the government. Now the first appeals court to have considered the issue after adversarial presentation has concluded, in an opinion that no one could characterize as anything other than meticulous and comprehensive, that the program is illegal. The Second Circuit’s opinion is respectful towards the FISA court and the congressional intelligence committees, but there is no doubt that the opinion is an indictment of the oversight system.

2. The ruling means that even if Congress reauthorizes Section 215 by June 1, the government will have to discontinue bulk collection under that provision unless Congress adds language expressly authorizing bulk collection or the government prevails on the Supreme Court to vacate the ruling. That the Second Circuit declined to enjoin the call records program is immaterial. If Congress reauthorizes Section 215 in its current form, the district court will likely issue an injunction. Even without an injunction, telecommunications providers may begin to resist compliance with production demands.

3. The ruling means that the government will have to reconsider other bulk collection programs that are operated under other authorities but predicated on the same now-discredited theory of “relevance.” We know the DEA had a bulk call records program until 2013. We know the NSA was collecting Internet metadata in bulk until 2011. In what contexts the government is engaging in bulk collection now is not entirely clear, but news reports indicate that there are other bulk collection programs that haven’t yet been officially acknowledged. If the government is operating other bulk collection programs — or even “bulky” collection programs — it will now have to reconsider them. Even if it doesn’t reconsider them of its own accord, private entities whose assistance the government needs (telecommunications companies, financial companies, technology companies) may resist demands that they might not have resisted before last week. I suspect that general counsels of corporations that hold large volumes of third-party records will read the Second Circuit’s decision especially closely.

4. The ruling will change the dynamics on the Hill — and to some extent it already has. The Senate majority leader was already struggling to marshal support for a straight reauthorization of Section 215. Now his task is harder, first, because the Second Circuit’s ruling makes it even clearer that the Patriot Act’s surveillance provisions are being abused; and, second, because, again, even a straight reauthorization won’t enable the government to continue bulk collection under Section 215 unless the Supreme Court vacates the Second Circuit’s decision. The flipside is that the leverage of the USA Freedom Act’s supporters has increased, and they may be able to use that leverage to strengthen the Act — for example, to tighten the restriction against bulk collection under Section 215, to impose stronger minimization requirements, to require greater transparency about the government’s surveillance activities, and to prohibit “backdoor” searches under the FISA Amendments Act. If the USA Freedom Act isn’t strengthened, some who previously supported it may ask whether it accomplishes significantly more than what the Second Circuit has already accomplished, and they may begin to wonder why Section 215 shouldn’t simply be allowed to sunset. On the other hand, if the reform bill is significantly strengthened, it may attract support from organizations and individuals that haven’t until now been willing to support it. (Currently, the ACLU is neither supporting the bill nor opposing it.)

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It will be easier to say in three years, or perhaps even three months, precisely how significant the Second Circuit’s decision was. But the decision has already shaken things up, and it could change the government’s surveillance practices quite dramatically. I wrote two years ago that the Snowden disclosures should spark reform, and I wrote here nine months ago that they would. It’s too early to know whether I was right, but I’m more optimistic today than I was a week ago.