Remember how shocked you were back in December of 2005 when you learned that the government was spying on Americans' phone calls and emails without warrants? The whistleblower who apparently kicked off that New York Times investigation has come forward, and his story is a timely lesson on how important -- and frightening -- it can be to do the right thing.

This weekend, Newsweek published the remarkable saga of Thomas M. Tamm, a former prosecutor in the Department of Justice who saw evidence of illegal domestic surveillance of U.S. citizens. When his questions to superiors went unanswered, Tamm decided to blow the whistle -- calling the New York Times from a pay phone. James Risen and Eric Lichtblau eventually won the Pulitzer Prize for their work in uncovering the scandal that touched the highest levels of our government.

The Risen and Lichtblau investigation sparked another important development: it showed former AT&T employee Mark Klein the context of the work he did in a secret room in San Francisco. Mr. Klein decided the time had come for him to blow the whistle himself. His evidence formed the backbone of our class-action lawsuit against AT&T.

But this whistleblowing does not come without risk. The Newsweek article includes a harrowing account of an FBI raid on Tamm's home. And he is still worried about facing legal charges for his actions. But without Tamm, America may have never learned about this massive illegal spying by the National Security Agency, and we all owe him our thanks.