Abstract: Many people believe that when national security is threatened, federal courts should defer to the government. Many other people believe that in times of crisis, citizens are vulnerable to a kind of "panic" that leads to unjustified intrusions on liberty. But to date, there is little information about what federal courts have actually done in this domain, especially in the period after the attacks of September 11, 2001. On the basis of a comprehensive study of relevant courts of appeals decisions in the aftermath of those attacks, this essay offers four findings. First, the invalidation rate is about 15 percent - low, but not so low as to suggest that federal courts have applied a broad rule of deference to government action. Second, the division between Republican and Democratic appointees is comparable to what is found in other areas of the law; contrary to reasonable expectations, there is no significant "compression" of ideological divisions in this domain. Third, and perhaps most strikingly, no panel effects are apparent here. Unlike in the vast majority of other areas, Republican and Democratic appointees do not appear to vote differently if they are sitting with Republican or Democratic appointees. Finally, judicial behavior cannot be shown to have changed over time. The invalidation rate is not higher in recent years than it was in the years immediately following the 9/11 attacks. Explanations are ventured for these various findings, with particular reference to the absence of discernible panel effects.