In 1971, President Richard M. Nixon went to war with the press over a classified leak published in The New York Times. It was called the Pentagon Papers and it became one of the most storied leaks in American history.

Weighing in at 7000 pages, the report revealed how president after president had misled the public about their country’s role in escalating the Vietnam War. But the leak’s true importance came in the Supreme Court, which, in ruling against Nixon’s attempt to bar publication of the report, set strict limits for future presidents who might wish to do the same.

The Pentagon Papers case was a watershed moment for press freedom and for the public’s right to know many government secrets. But the ruling left open a potent weapon to go after leakers — the Espionage Act. Now, almost five decades later, leakers are not the only ones worried about being in its crosshairs as the Trump Administration’s war with the media has again raised the same high-stakes question — what do the American people have a right to know?