In the aftermath of Edward Snowden’s historic disclosures and flight from the United States, many Americans took to the airwaves and social media to argue, dissect his choices, and opine on his possible motives. Was he a coward? A hero? A traitor? A patriot?

The issues evoked in those debates are at the heart of Lloyd C. Gardner’s The War on Leakers. Gardner, an emeritus diplomatic historian at Rutgers, attempts to set the Obama White House’s prosecutorial assault on those who disclose classified information—most especially Snowden—in a historical context, highlighting the administration’s