Protest signs aren't enough to keep the NSA's superpowers in check. Photographer: George Frey/Bloomberg
Protest signs aren't enough to keep the NSA's superpowers in check. Photographer: George Frey/Bloomberg

The National Security Agency typically uses its vast powers for good. But like a conflicted superhero, it faces the constant temptation to put them to some darker purpose.

President Barack Obama has -- slowly, grudgingly, tentatively -- agreed to curtail one of the agency's most seductive powers: the ability to collect and store huge amounts of information about Americans' phone calls. Several similar plans circulating in Congress suggest a consensus is emerging that this program, known as Section 215, has been out of bounds. And while it won't be easy to transmute that consensus into an enforceable law, the effort is a first step toward ensuring the NSA remains a force for good.

Besides intentionally targeting Americans, which intelligence agencies aren't supposed to do, the 215 program is intrusive -- recording and storing what numbers you called, when and for how long -- and legally dubious. A federal judge has called it "almost Orwellian" and a probable violation of the Constitution.

The program's clearest flaw, however, is that it's ineffective. Two recent high-level reviews have concluded that it hasn't been instrumental in a single major terrorism investigation.

Obama's proposal would end the program in its current form. It would let phone companies, rather than the NSA, hold on to the call records, and then require that intelligence agencies get court approval -- except in emergencies -- before they collect data from the companies on any given phone number. It would also help the NSA: With these safeguards in place, the agency would be able to access mobile phone records that had previously been beyond its reach.

That's progress. But Congress, which is now considering several bills on the topic, will ultimately have to settle the matter. Representatives Dutch Ruppersberger and Mike Rogers of the House intelligence committee put forward the latest bill last week. And though their plan is flawed -- it requires no judicial approval before conducting a search, for instance -- it's one more sign that broad agreement should be possible.

Any legislation Congress settles on should follow Obama's lead in requiring a judge's approval before spies can access U.S. calling records. It should clarify what limitations will be placed on the government's ability to search information collected from innocent Americans who may be in the contact chain of a suspect. It must resolve technical challenges that could impede the phone companies from sharing information quickly when needed. And the wording of the law must be explicit and precise: The NSA makes linguistic distinctions that would challenge a medieval Scholastic.

Such a bill would redress one of the most troublesome aspects of the NSA's dragnet. But Congress is still missing a bigger opportunity. Since the Sept. 11 terrorist attacks, the U.S. intelligence community has attained more legal leeway, more money and -- critically -- more powerful tools for conducting surveillance than ever before. As a result, its approach to espionage has morphed from targeting specific suspects to collecting as much information as possible, from as many sources as possible, to amass databases for later search.

That's a substantial shift. And Congress is missing a chance to make the law responsive to it. The NSA revelations offer the legislature an opportunity to rethink, as it did before starting in 1975, the fundamental rules by which the U.S. conducts intelligence.

Every superhero has his flaws. Keeping them in check requires an awful lot of vigilance.

To contact the senior editor responsible for Bloomberg View's editorials: David Shipley at davidshipley@bloomberg.net.