In “Crisis and Command,” his sweeping history of presidential prerogatives, John Yoo argues that national security crises inevitably ratchet up the power of the president at the expense of Congress. “War acts on executive power as an accelerant,” he writes, “causing it to burn hotter, brighter and swifter.” In “Bomb Power,” Garry Wills argues much the same thing, adding that the advent of atomic weapons has made this concentration of power in the White House even greater. “The executive power increased decade by decade,” he writes, “reaching a new high in the 21st century — a continuous story of unidirectional increase.” Where the two authors disagree is on whether this trend should be celebrated or denounced. Yoo finds increased executive power appealing and in accord with the Constitution. Wills finds it appalling and a constitutional travesty.