Courts do not generally occupy a prominent role in times of war and conflict. Their slow and deliberate pace in resolving questions of importance is particularly unsuited to the demands posed by security threats. They have an informational disadvantage against the executive concerning credible threats and security concerns, and their lack of electoral accountability to the public make them particularly bad actors to decide on issues that risk serious harm to the country. In no other time are otherwise strong courts as weak against the executive as when the country is facing a security threat. At the same time, actions taken by the government to counter security concerns arising from war (or terrorism) are likely to limit accountability to the branches and restrict civil liberties of individuals. Besides its normative appeal, the role of courts in times of war is an interesting empirical question that spans institutional puzzles, such as court independence and legitimacy, on the one hand, and behavioral ones about the disparate impact of security concerns on judges of different policy preferences or loyalties, on the other. This chapter provides an overview of how the work so far has contributed to what we know and do not know about judicial decision making in times of war. I apply the extant literature on war and courts to a comparative empirical analysis of the effect of war on the Appellate Committee of the House of Lords, the Supreme Court of Canada, and the United States Supreme Court. Quantitative analyses on wartime courts outside of the US are rare, with none spanning more than one country. The analysis looks at high court decisions in cases involving the government to provide some insight into how and why court and executive responses to war vary across similar nations. How do courts counter executive interests as these government actors adjust to the changed security perceptions at wartime? Analyzing the universe of cases involving the government for each of the three countries under analysis, I find systematic changes in the treatment of government interest in courts due to war. The nature of these patterns differs across the three countries, revealing only one court willing to rein in the government as security concerns place courts in a disadvantaged position.