Earlier this month, the Reporters Committee for Freedom of the Press created a visualization of the uptick over the last decade in news media “leak” prosecutions — that is, criminal cases against journalistic sources for the unauthorized disclosure of government secrets to the press. The visualization builds on research by the Technology and Press Freedom Project at the Reporters Committee over the last year to catalogue all cases involving either formal leak investigations or prosecutions throughout history.

That research paints in stark relief the dangers from overclassification in particular. Dogged newsgathering is one of the only ways to hold the military, intelligence agencies and federal law enforcement accountable, particularly given the expansive authority that they claim in order to keep secrets.

Overclassification has been a concern for decades. In a 1989 opinion piece for The Washington Post, the former U.S. Solicitor General who argued the Pentagon Papers case for the government, trying to block publication of certain parts of a classified history of the Vietnam War, switched sides.

In his op-ed, Erwin Griswold warned of too many government secrets, writing, “It quickly becomes apparent to any person who has considerable experience with classified material that there is massive overclassification and that the principal concern of the classifiers is not with national security, but with governmental embarrassment of one sort or another.”

Given the government’s aggressive use of spying laws to prosecute leakers over the last decade that the Reporters Committee’s research on leaks shows, the problem of overclassification has taken on a new urgency. When government information is improperly classified — particularly when the information could be embarrassing or reveal misconduct — it creates an added incentive for government employees to leak it, and the increased volume of classified information makes government secrets harder to keep.

Overclassification typically refers to adding an unneeded classification level to a document. This could mean classifying a document that doesn’t need to be, or upping a document’s classified level, for example from “confidential” to “secret” or “secret” to “top secret.” Overclassification can also refer to keeping information classified for longer than necessary, or keeping it compartmented, meaning that even individuals with security clearances can’t access it.

Overclassification occurs for a number of reasons, one of which is the lack of uniform procedures across agencies. In a 2017 report, the Information Security Oversight Office at the National Archives, known as ISOO, found almost 3,000 active security classification guides across various agencies.

There’s also a lack of incentives to avoid overclassification. While there are negative consequences for improper disclosure, there aren’t for overclassification. When national security is involved, for example, virtually everyone agrees with Griswold that classifiers will usually err on the side of caution and keep things secret.

In 2016, former ISOO director J. William Leonard testified before the House Committee on Oversight and Reform that overclassification is “rampant” in the executive branch, and wrote, “The opaque nature of the classification system can give the government a unilateral and almost insurmountable advantage when it is engaged in an adversary encounter with one of its own citizens, an advantage that is just too tempting for many government officials to resist.”

Senator Dianne Feinstein (D-Calif.), the former chair and vice-chair of the Senate Select Committee on Intelligence and a frequent defender of the Intelligence Community, has also expressed concern. “Congressional overseers and the public must be given appropriate insight into government activities, as well as their legal rationale, to ensure America’s values are being upheld and our interests advanced,” she wrote.

Overclassification harms not only transparency, but also security. For instance, the 9/11 Commission Report prominently criticized excessive compartmentation — permitting access to information only on a “need to know” basis. “Such a system implicitly assumes that the risk of inadvertent disclosure outweighs the benefits of wider sharing. Those Cold War assumptions are no longer appropriate,” the report said.

Partly because too much information is classified, prosecutors are typically wary of using spying laws — which criminalize the unauthorized disclosure of classified information — against journalistic sources. Until about a decade ago, there had been only one successful prosecution of a journalist’s source under the Espionage Act — that of Samuel Loring Morison — and only a handful of unsuccessful attempts. To the extent they were punished, leaks would lead to the loss of one’s security clearance or termination.

But that has changed dramatically. During the eight years of the Obama administration, the Justice Department prosecuted 11 cases against government employees who publicly disclosed secret government information. In the 2 1/2 years of the Trump administration, there have been seven such cases, though not all are under the Espionage Act.

This past May, for the first time in American history, the government successfully obtained an indictment that includes espionage charges based solely on the act of publishing classified information online. Although the government stated that the defendant, Julian Assange, “is no journalist,” the legal theory prosecutors are using would punish activities such as the solicitation, receipt and publication of classified information.

Finally, both the House and Senate recently passed a bill that would expand criminal penalties for disclosing the identities of undercover intelligence officers and agents. Congress enacted the original law, the Intelligence Identities Protection Act, in 1982 after six years of debate. It is rarely used because Congress drafted it narrowly to apply only in cases where there’s a real risk of harm to the officer or agent. Congress, however, is poised to extend it to cases where officers or agents are safe on U.S. soil, or are even retired or deceased.

For most of American history, partly because of First Amendment concerns and partly because everyone knows the government overclassifies, prosecutors took a relatively hands-off approach to the unauthorized disclosure of government secrets. But now the Justice Department has a new and significant desire for these cases, and is even willing to prosecute just the act of publishing government secrets. The threat posed by overclassification — a threat that even the main government lawyer in the Pentagon Papers case recognizes — is thus all the more critical to address.