If you think investigations of media leaks are confined to issues of national security, think again.

Since 2008, one particular federal government agency has aggressively investigated leaks to the media, examining some one million emails sent by nearly 300 members of its staff, interviewing some 100 of its own employees and trolling the phone records of scores more.  It’s not the CIA, the Department of Justice or the National Security Agency. 

It’s the Securities and Exchange Commission. 

Details of the SEC’s latest inquiry were recently revealed, when CNBC and Reuters reported that the agency’s Office of the Inspector General (OIG) had examined the email and phone records of 39 SEC employees. The goal: To find out who had leaked to Reuters information on the commission’s settlement with JP Morgan over the “London Whale” trading charges.

The March 2014 OIG report, which itself was leaked to the press, said investigators had also interviewed 53 SEC employees, including the chair, Mary Jo White, and the four other commissioners. They also reviewed the building logs to find out when Reuters reporters visited the SEC headquarters.

All that effort was for naught. Despite the time and resources that have been poured into them, none of the SEC’s eight investigations in the past six years have uncovered the leakers. (See the details in the table here.) Five years ago, OIG investigators tried to find the sources of a Wall Street Journal story on a leaked SEC report examining how ratings agencies failed to accurately assess the risks of mortgage-backed securities. They interviewed 37 employees and reviewed nearly 150,000 emails but failed to find their target.

The zealousness of these probes is worrisome. Leak investigations send a chilling message to both journalists and their sources. They can also impede legitimate newsgathering and curtail reporting that seeks to hold government to account. 

The SEC is a powerful agency with a big mandate that dates back to the stock market crash of 1929: To protect investors and maintain fair and functioning markets. That role has become even more important since the 2008 financial crisis.

The SEC is the enforcer of the law for the financial sector. Its success or failure in regulating companies and reining in the excesses of financial institutions are matters that concern not just the U.S. public but, given the global contagion that followed the collapse of Lehman Brothers in 2008, also the world.

More, not less, media scrutiny of the SEC would do us all some good. To some extent, our economy depends on how well the SEC does its job, the wisdom of its decisions and enforcement actions, and its ability to ensure that the 2008 disaster is not repeated.  The leaks provide public insight into how the SEC works, even if they do disclose information that may inconvenience the agency.

The SEC doesn’t share that view.  It argues that it needs to lay down the law and stanch the flow of leaks that might yield market-moving information. But even a cursory review of information “leaked” to the media suggests that the SEC only jumps on the trail when it suits the agency’s goals.

In just the past three months, many articles have been published that seem to rely on leaks similar to those that the OIG has so ardently probed. The stories include a Wall Street Journal report that revealed the SEC is investigating JP Morgan for steering its clients to its own investment products and away from those offered by outside firms, as well as a Reuters story on an SEC inquiry into whether brokerage houses are providing their clients the best price and most efficient execution of their trades. The source for the stories? “People close to the probe” and “several people familiar with the matter.”

There seems to be a double standard: Inconvenient leaks are investigated; beneficial ones, tolerated. As a journalist who has followed the SEC for many years says, “It appears that the agency has a long history of leaking information of a self-serving nature, giving the appearance that it is doing its job investigating companies.”

At the heart of the most recent investigation was Sarah N. Lynch, a Washington, DC-based reporter for Reuters who was suspected of having received information that had not been authorized for disclosure.

[Disclosure: Lynch was my student at the Columbia Journalism School’s Stabile program in 2007-08 and my partner is a senior editor at Thomson-Reuters.] 

Sheila S. Coronel is the dean of academic affairs at Columbia University Graduate School of Journalism.