The NSA has some welcome news. Photographer: David Trood/The Image Bank via Getty Images
The NSA has some welcome news. Photographer: David Trood/The Image Bank via Getty Images

The National Security Agency has come in for a lot of criticism in the past year, some of it justified, as news has leaked out about its colossal global espionage operations. There was news of a different sort yesterday: The NSA has a power that actually isn't being abused. The challenge now is how to keep the agency on the straight and narrow.

The Privacy and Civil Liberties Oversight Board, an independent executive agency, found that the NSA has legally and effectively used its authority under Section 702 of the FISA Amendments Act. That section allows the NSA to monitor electronic communications -- including the content of phone calls and e-mails -- in search of foreign intelligence. The catch is that it has to reasonably believe that its targets are non-Americans and outside the U.S.

The NSA’s Gigantic Haystack

Under this authority, the NSA gathers more than 250 million Internet communications a year. It can intercept information on 193 countries. In 2013 alone, it targeted nearly 90,000 foreign groups and individuals for surveillance.

That's the kind of thing that infuriates U.S. allies. But it's legal, and much of it has proven quite valuable: The board found 20 cases in which such surveillance aided counterterrorism investigations, and 30 in which it identified previously unknown terrorists or plots. More than 100 people have been arrested as a result.

The board also found no "evidence of bad faith or misconduct" in using the program.

That's not to say it's without problems. Sometimes the communications of innocent U.S. persons -- a term of art that includes U.S. citizens, companies and permanent residents -- also get swept up, whether accidentally or because they were in contact with a foreign target.

A lot of regulations cover the use of these data. But the NSA asserts that, once collected, it can be lawfully searched by its agents and others. The Central Intelligence Agency conducted about 1,900 queries of such information in 2013. The Federal Bureau of Investigation, alarmingly, says it doesn't track how often it accesses the communications of Americans gathered under this program but "believes the number of queries is substantial."

In fact, the report says that the government has no idea how much data it collects on Americans, and it notes that the rules "potentially allow a great deal of private information about U.S. persons to be acquired."

The board was split on exactly how to treat that information, an issue that gets pretty complicated. But the bottom line is this: If intelligence agencies are intentionally sifting through these data for the content of specific Americans' communications, they should get a warrant -- except in emergencies -- just as the Constitution requires in all other cases. This was the standard recommended by the president's NSA review panel in December. And it's the standard the House of Representatives voted to affirm last month. The Senate should do the same.

The board offered a few other suggestions, which it says are "designed to push the program more comfortably into the sphere of reasonableness." That's a phrase only a panel of lawyers could love, but their reforms are mostly thoughtful and measured, designed to mitigate gaps in oversight and compliance. They also recommend clarifying when spies can target foreigners -- a step that may, someday, help soothe the ire of U.S. allies.

Section 702, as the panel's report shows, gives the NSA a lot of power. Making sure it's only used against the right people will require a lot of vigilance, too.

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