Jonathan Zimmerman teaches history and education at New York University. He is the author of “Small Wonder: The Little Red Schoolhouse in History and Memory” (Yale University Press).

Did the White House misrepresent the Benghazi, Libya, attacks to cover up its own ineptitude? Did the Internal Revenue Service purposefully target conservative groups for scrutiny?

Americans rely on journalists to cast light on these thorny issues. But if reporters can’t do their jobs, everyone else will most likely remain in the dark about serious government mistakes.

That’s why all Americans should be deeply alarmed about the Obama administration’s recent investigations of news organizations, which have drawn far less ink than the Benghazi or IRS scandals. And that’s exactly backward. The most worrisome threat right now is to the people who actually produce the ink: US journalists.

The Obama administration appears to be backpedaling from its overstep since drawing a backlash from media organizations over recent reports about Justice Department investigations of reporters. Attorney General Eric Holder held a meeting with several media outlets yesterday to discuss possible changes to guidelines for the department's investigation of journalists. But several media outlets boycotted the meeting because it was off the record. And at the meeting, media representatives reportedly registered concerns that these leak investigations have had a chilling effect on both reporters and government officials....