Snowden's leak meets those tests. Urging clemency for Snowden is not a radical case against our existing system of rules—it is an acknowledgment that, like all rules, ours are imperfect. One of the finest presidents, George Washington, pardoned farmers who took up arms against the federal government (!) to protest a tax on whiskey. He wouldn't have granted those pardons had he thought that he was making a radical case against the legitimacy of the U.S. government or setting a precedent for anti-tax insurrections. And it is difficult to argue that any such precedent was set, even at the dawn of the federal republic when norms were still being established.

Today, it is even more difficult to imagine that a pardon for Snowden, or one of the lesser forms of forgiveness the Times advocates, would cause other federal employees to imagine that they'd avoid punishment if, say, they made public the identities of American spies abroad or secret codes from the U.S. nuclear program. As a political matter, the fallout would be dramatically different. And it isn't as if plea bargains, grants of clemency, or pardons given to one man impose any sort binding precedent in the fashion of a Supreme Court ruling. In the unlikely event that forgiveness for Snowden caused anyone to start leaking other secrets, correcting the problematic "precedent" would be one swift prosecution away.

I trust that if the national-security state were drawing up a classified assassination list of American journalists even Barro would be amenable to a pardon for a federal employee who violated secrecy laws by leaking its existence to the press. He isn't opposed to forgiveness for any possible leaker—he just doesn't think Snowden in particular is worthy. So it seems to me that he doesn't just overstate the costs of a pardon for Snowden, he also neglects to acknowledge or address the unusually powerful reasons for granting one in this of all cases. When should a leaker of government secrets be forgiven rather than jailed? Here are some possible standards:

When the leak reveals lawbreaking by the U.S. government

When the leak reveals behavior deemed unconstitutional by multiple federal judges

When a presidential panel that reviews the leaked information recommends significant reforms

When the leak inspires multiple pieces of reform legislation in Congress

When the leak reveals that a high-ranking national-security official perjured himself before Congress

When the leak causes multiple members of Congress to express alarm at policies being carried out without their knowledge.

The Snowden leak meets all of those thresholds, among others.

There is a final weakness in Barro's argument. He treats clemency for Snowden as if it would meaningfully weaken norms against leaking classified information even though people in power leak classified information all the time without being punished for it. Jack Shafer made this vital point at length in a column published almost immediately following the first stories sourced to Snowden. "Without defending Snowden for breaking his vow to safeguard secrets," he wrote, "he’s only done in the macro what the national security establishment does in the micro every day of the week to manage, manipulate and influence ongoing policy debates."