The separation of powers becomes increasingly stressed during wartime, as power is traditionally accumulated by and consolidated in the executive. This article asks to what degree the separation of powers collapses by examining judicial deference to the executive during wartime. By analyzing a set of cases in the courts of appeals from a 100-year time period, this article demonstrates that while judicial preferences undergo a fundamental shift with respect to criminal cases, there is no evidence of heightened deference to the executive during wartime. These findings suggest that a state of war has a preference-altering effect on judicial treatment of criminal defendants. They further suggest that concerns about judicial deference to the executive during times of war may not be as serious as conventional wisdom suggests.