The First Amendment protects not a privileged group of people called “professional journalists” but rather an activity: namely, using the press to inform the public about what the government was doing.

From the Vietnam War era to today -- from aerial bombing and torture to ecological disasters and financial scams moving billions of dollars into private pockets—the high-up secrecy hiding key realities from the public has done vast damage. No wonder economic and political elites despise WikiLeaks for its disclosures.

His skin is pale from years without sunlight, matching his prematurely white hair. But his resolve is unbroken, and the leaks he originally sought to publish when he founded WikiLeaks almost 10 years ago are still reaching the light of day.

Governments, militaries, corporations, banks: They all stand to lose the control they exert over society when information they suppress runs free. Yet some of the most ardent advocates for the free Internet have become targets of these very institutions, forced to live on the run, in exile or, in some...