For those who suppose the Constitution smoothly and efficiently settles disputes among the branches—like the storied “machine that would go of itself”—the war power has always proven a vexing exception. The text is vague, the history inconclusive, and the practice contested. While this state of affairs has not kept scholars from advancing one claim or another on the “correct” allocation of power between the executive and legislative branches, it has (and always will) prevent one school of thought from achieving conclusive dominance over all others. Faced with this, some scholars have argued that disputes about the war power are essentially political and cannot be intelligently analyzed using traditional legal tools—a view I generally share.

But in an ambitious new book, University of Michigan political scientist Mariah Zeisberg takes a different view. In War Powers: The Politics of Con­stitutional Authority, Zeisberg carefully unpacks the language and structure of the Constitution and combines this analysis with a nuanced appraisal of the relative strengths and weaknesses of the executive and legislative branches vis­a-vis the war power (their respective “governance capacities” [p. 26] to develop ostensibly neutral “pro