“If you see something, say something.” That’s what our homeland security apparatchiks incessantly preach. But 13 years after the Sept. 11 attacks, the freedom to warn is in danger and vigilant whistleblowers are under fire.

Listen to Robert MacLean. He’s a former Air Force nuclear weapons specialist and Border Patrol agent recruited by the government to serve as one of the first federal air marshals after Sept. 11.