A century ago, on June 15, 1917, Congress passed the Espionage Act. This law against interfering with military efforts, including recruitment, or providing information “useful to the enemy” offers a popular piñata for historians and civil libertarians. But while whacking away at this sweeping, seemingly illiberal, law—boom, surprise—some liberal goodies pop out.

The centurion is showing unexpected vigor these days. Not surprisingly, the Trump administration arrested its first leaker under this law. More surprisingly, Barack Obama’s administration used the law to prosecute more leakers than all previous presidents combined.

Democracies face two contradictions in combating espionage. Countries cannot survive without limits—but democracies cannot survive without limiting those limits. In classifying information, government of the people and by the people declares it doesn’t trust the people. Yet we must keep secrets to protect our troops while preserving the freedoms they fight to preserve.