Ellsberg says that Kissinger listened carefully, but “I knew it was too soon for him to appreciate fully what I was saying. He didn’t have the clearances yet.”

What’s striking about the account isn’t just its wry brilliance. It is that the man who defined the modern category of whistle-blower was the sort who gave career advice to Henry Kissinger. Ellsberg was an insider—and that fact puts him in stark contrast with the man who has come to be seen as his heir, Edward Snowden.

Snowden left his job as a National Security Agency contractor in Hawaii three years ago, with thousands of the U.S. government’s most closely held secrets in his possession. In the course of his work, Snowden had learned things that dismayed him, and many of those secrets soon found their way onto the front pages of the world’s newspapers, earning him his reputation as the post-9/11 Ellsberg.

But Snowden did not study under a Nobel Prize winner, or give career advice to the likes of Henry Kissinger. He was a community-college dropout, a member of the murky hacking counterculture. He enlisted in the Army Reserves, and washed out after twenty weeks. He worked at the C.I.A. for a few years and left under a cloud. He learned about the innermost secrets of American intelligence-gathering and policy not because he was personally involved with that intelligence-gathering or policymaking but because he was a technician who helped service the computer systems that managed these things. The élites, Snowden once said, “know everything about us and we know nothing about them—because they are secret, they are privileged, and they are a separate class.” Had Snowden been a whistle-blower in 1967, at the launch of the Pentagon Papers, he would have blown the whistle on Daniel Ellsberg. The whistle-blower as insider has become the whistle-blower as outsider. That is a curious fact, and, as we come to terms with the consequences of Snowden’s actions, it may be an underappreciated one.

In “The Leaky Leviathan,” a study published three years ago in the Harvard Law Review, David Pozen attempts to understand a puzzle. Strict laws prohibit government officials from disclosing secrets, yet leaking has been a constant feature of American political life. Since the passage of the Espionage Act, in 1917, the federal government has prosecuted only about a dozen cases concerning media leaks of state secrets. That’s an astonishingly small number. Pozen, a Columbia law professor, cites one estimate that, between 1949 and 1969, 2.3 per cent of the front-page stories in the Times and the Washington Post were based on government leaks. Another study looked at just the first six months of 1986 and found that a hundred and forty-seven stories in the country’s eight major newspapers were based on leaks. The entire career of Bob Woodward, perhaps the best-selling political writer of his generation, is based on leaks. And yet, with a few symbolic exceptions, nothing is done.

“For a crime that Presidents describe as a major threat to national security and good government, the degree of ‘underenforcement’ is stunning,” Pozen writes. “Even if we were to limit the denominator to classified information leaks that the Intelligence Community (IC) is known to have otherwise documented publicly—which may be a small fraction of the universe of potentially prosecutable offenses—the historic indictment rate for leak-law violators would be below 0.3%. The actual rate is probably far closer to zero.” Even the recent uptick in leak prosecutions during the Obama Administration, Pozen argues, does not alter the fundamental pattern. In Washington, giving away secrets to the press is a crime largely without consequences.

Pozen easily dispenses with the idea that Administrations don’t prosecute leakers because they can’t find them. They can: information—particularly sensitive information—has a pedigree. When I worked on the science desk at the Washington Post, my colleagues and I would read a front-page story by our counterparts at the Times and invariably know where the leak on which the story was based came from. The first order of business was typically to call the leaker and complain that he or she was playing favorites.

Pozen argues that governments look the other way when it comes to leaks because it is in their interest to do so. He cites a story that ran in the Wall Street Journal and the Washington Post in 2012 about how the C.I.A., with the coöperation of Yemeni authorities, was using drone strikes against Yemen-based Al Qaeda militants. The drone program was classified: that story didn’t come from a press conference. Pozen says the story was clearly a “plant”—that is, a leak made with the full authorization of the White House. Letting the facts slip out served a purpose for the Obama Administration. A plant like that, Pozen writes, “keeps the American people minimally informed of its pursuits, characterizes them in a manner designed to build support, and signals its respect for international law.”

But if you want to reserve your right to plant an authorized leak, Pozen argues, you have to allow unauthorized leaks as well:

For a strategy of planting to work, it is critical that relevant audiences not immediately assume that every unattributed disclosure they encounter reflects a concerted White House effort to manipulate the information environment. The practice of planting requires some amount of constructive ambiguity as to its prevalence and operation.

In a world where every stealthy disclosure is a plant, the journalist is a stooge, the Administration’s motives are transparent, and the government of Yemen is exposed. But, when the origin of the disclosure is uncertain, all parties save face. “Plants need to be watered with leaks,” Pozen writes. He continues, “It is loosely analogous to what a game theorist would call mixed-strategy equilibrium: an approach that generates sufficient randomness (or apparent randomness) across government sources as to degrade the ability of outsiders to predict the nature and origin of any given disclosure.”

Leaks are also a form of governmental “self-binding,” Pozen argues. The executive branch, he says, has a persistent problem in the American democratic system. It needs to justify to the public the extraordinary power it wields. One of the ways it does this is to allow periodic disclosures that let the voters and the Congress see behind the curtain, reassuring them that most of the troubling things the executive branch engages in will eventually come to light. The White House allows leaks—even if those leaks hamper and embarrass it in the short run—because they help it maintain its power in the long run. The public needs regular and convincing reassurance that the strong President will be caught before he becomes a bad President. “A mechanism that never made the President look bad would quickly lose its capacity to signal credibility; the whole point is that the power-enhancing second- and third-order effects of these arrangements ultimately come to swamp the power-reducing first-order effects,” Pozen writes. “No pain, no gain.”