It has finally happened: a nonsecret federal court in Washington has asked whether it violates your privacy for the National Security Agency to intercept all (yes, all) phone calls in the United States and record the metadata connected to them. And what do you know? The court, in a case called Klayman v. Obama, concluded that it probably did. Then it ordered the government to stop. Hallelujah!

The district court’s order of a preliminary injunction could well be overturned. The Barack Obama administration will almost certainly appeal, claiming that national security is impinged, not to mention that no individual has standing to sue.

But the decision, however fleeting it turns out to be, provides a perfect opportunity to ask just what we’ve learned about secrecy and government in this year of Edward Snowden. The court’s decision concentrates the mind on an obvious fact that we have a tendency to forget when debating whether the superleaker was a traitor, a hero or both: In any rational constitutional world, the public and the courts alike would not have allowed the domestic spying that the National Security Agency has been systematically performing.

Before Snowden’s revelations, many cynical observers of national security surveillance already believed that the government was collecting information on all communications that it could get its hands on globally. After all, as early as 2003, the government had a plan in place that it explicitly (if briefly) called Total Information Awareness. To those familiar with the aspirations of intelligence services, if not always their operations, the logic was straightforward: If the technology exists to gather the intel, it’ll be gathered. And there was no doubt that the technology existed.

That prior supposition was what made it so difficult to judge Snowden’s actions in revealing the scope and extent of NSA intelligence gathering. On the one hand, he was telling us what many of us already believed — which made it seem as though the revelation wasn’t especially harmful, but also that it wasn’t particularly revelatory. On the other hand, assumption is different from certain knowledge. The latter creates a concrete ground for debate — and so it also makes it clear why the government wanted the information to remain secret.

Probably the most important lesson of the last year is that Snowden’s actions definitively changed the terms of the debate about surveillance, both domestically and internationally. In historic terms, therefore, it was important, not trivial or a sideshow.

The legal sphere provides one striking example. In February, before Snowden went public, the Supreme Court in the case of Clapper v. Amnesty International USA refused to consider a suit alleging statutory and constitutional violations of the Foreign Intelligence Surveillance Act. Justice Samuel Alito, writing for a 5-4 majority, held that the plaintiffs couldn’t bring the case because they had “no actual knowledge of the government’s … targeting practices” and could “merely speculate and make assumptions about whether their communications … will be acquired.”

Now, after Snowden, this conclusion would be far harder to reach with a straight face. Indeed, Judge Richard Leon began his discussion of the facts in the recent Klayman case with the fact that the Guardian newspaper published Snowden’s first leaks in June. The leaks led the government for the first time to acknowledge the existence of the program to collect domestic calls — which Leon held was sufficient to give the plaintiff standing. No Snowden, no case.

A related, hugely important lesson of the post-Snowden era is that public scrutiny connected with known facts is necessary to make the legal process work. A statute arguably authorizing universal surveillance was on the books, and it was public, but the interpretation of the statute under which the government considered itself authorized to perform the surveillance was secret. The Foreign Intelligence Surveillance Court had considered the meaning of the statute and its constitutional legitimacy — but that, too, had taken place in secret.

Secret interpretations of the law are tantamount to secret law. And secret law is the bane of democracy. It’s perfectly reasonable for the government to keep secrets about what it’s doing where national security interests are implicated. But there’s no good, democratic reason for the laws that authorize the secret behavior to be secret themselves.

So why did the government want to keep its legal interpretation secret? Not to gain an advantage over the terrorists, who certainly know that we’re listening. No, the government wanted to protect itself from us — the people themselves. So long as surveillance was at least nominally secret, serious public debate about the right balance between privacy and security could largely be avoided, not only in the courts but in public discourse as well.

Witness the modestly hypocritical behavior of state leaders in Germany and Mexico who were faced with repeatable proof that the U.S. had tapped their phones. Of course they knew, or should have known, that their communications were not sacrosanct to their ally.

But being confronted with the brute facts changed the nature of the debate. Domestic audiences in those allied democracies were upset about the surveillance, just like we in the U.S. can now be more openly upset about violations of our own privacy rights. Making the debate concrete turns out to make all the difference.

Snowden’s actions, then, really were game-changing in that they moved the debate from informed speculation to straightforward reality. In the end, the law he broke really mattered. It will now be up to those who believe we are better off not knowing the facts to argue that those legal protections should be redoubled.

To judge whether they’re right, keep in mind this simple test: We don’t need to know everything the government is doing to keep us safe. We do need to know which laws we’ve passed to authorize the government to protect us — and that, in the end, is what makes us a democracy.

Noah Feldman, a law professor at Harvard University and the author of “Cool War: The Future of Global Competition,” is a Bloomberg View columnist.

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