CIA Realizes It's Been Using Black Highlighters All These Years | The Onion - America's Finest News Source
http://www.theonion.com/content/node/43014
"According to the report, sections of the documents— "almost invariably the most crucial passages"—are marred by an indelible black ink that renders the lines impossible to read, due to a top-secret highlighting policy that began at the agency's inception in 1947. "