In the intelligence world, as they say in spy novels, nothing is as it seems. So it goes with the National Security Agency.

In the six months since a former contractor began leaking details about the agency’s efforts to collect telephone data on a colossal scale, NSA officials have repeatedly asserted that the program is on firm legal ground. Just last week, NSA Director Keith Alexander reiterated that 15 separate judges on the secretive Foreign Intelligence Surveillance Court had upheld the program 35 times.

Now a federal judge has ruled that it probably infringes on the Fourth Amendment. In 68 pages of vivid if overexcited criticism, U.S. District Judge Richard Leon expressed disbelief at a program that he called “almost Orwellian” in scope.

“I cannot imagine a more ‘indiscriminate’ and ‘arbitrary’ invasion than this systematic and high-tech collection and retention of personal data on virtually every single citizen for purposes of querying and analyzing it without prior judicial approval,” he wrote. The government had failed, he added, to cite “a single instance” when the program had stopped an imminent terrorist attack.

How could a program that has been approved by all three branches of government (as intelligence officials like to say) be so clearly unconstitutional in the eyes of a federal judge?

Here’s one possibility: The FISA court, which has continually reauthorized the NSA’s telephone data collection, is hearing only one side of the argument. When the government argues for surveillance authority, it must show only probable cause that the target has some connection to a foreign government or terrorist group, a very low threshold.

As far as we know, no one argues against the government, or on behalf of U.S. citizens’ privacy interests. No telephone companies have ever challenged an order by the NSA to produce data before the court, even though the law provides a specific mechanism for them to do so. The entire oversight process seems resistant to argument -- or the clarity it can provide. The court’s top judge has admitted that it can’t independently verify what the government says about potential violations at the NSA.

Under such circumstances, it shouldn’t be surprising that the court has approved almost all the government’s requests. Or that NSA agents have systematically broken privacy rules, obfuscated before overseers, or occasionally used their vast powers to spy on love interests.

The judges should be hearing from more than one side.

Some lawmakers have advocated having a pool of independent lawyers act as “public interest advocates” in significant cases before the court. Orin Kerr, a law professor at George Washington University, has argued that the oversight section of the Justice Department’s national-security division should be able to review applications before the FISA court and oppose any it deems improper. Others have suggested that FISA judges themselves should be able to tap outside lawyers to challenge the government in cases that raise new legal issues and to appeal decisions in the government’s favor. Any of these ideas would be an improvement.

The public has no idea whether the NSA’s programs are doing much to keep us safe. What it does know is that, with each new revelation, these programs are diminishing American moral authority, raising suspicions about U.S. technology companies, and creating worldwide mistrust of the U.S. government.

The trade-off may, in the end, be worth it. Judge Leon may be wrong. But the best place to determine that balance is in the courts, in a properly adversarial contest.

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