You want a scary thought? Imagine a fanatic in the mold of Dick Cheney but without the vice president’s sense of humor.

In her important new book, “The Dark Side: The Inside Story of How the War on Terror Turned Into a War on American Ideals,” Jane Mayer of The New Yorker devotes a great deal of space to David Addington, Dick Cheney’s main man and the lead architect of the Bush administration’s legal strategy for the so-called war on terror.

She quotes a colleague as saying of Mr. Addington: “No one stood to his right.” Colin Powell, a veteran of many bruising battles with Mr. Cheney, was reported to have summed up Mr. Addington as follows: “He doesn’t believe in the Constitution.”

Very few voters are aware of Mr. Addington’s existence, much less what he stands for. But he was the legal linchpin of the administration’s Marquis de Sade approach to battling terrorism. In the view of Mr. Addington and his acolytes, anything and everything that the president authorized in the fight against terror  regardless of what the Constitution or Congress or the Geneva Conventions might say  was all right. That included torture, rendition, warrantless wiretapping, the suspension of habeas corpus, you name it.