The author first examines whether the temporary detention of cars at "sniper" checkpoints can be justified as "special needs" seizures that may be performed in the absence of individualized suspicion. A critical threshold issue is whether apprehension of a killer who is likely to strike again is a special need independent of the government's interest in general crime control. The article cites relevant case law to argue that apprehension of a particular, dangerous felon believed to be fleeing the area of a recently committed crime is a special need distinguishable from the state's generalized interest in crime control. It concludes, therefore, that in the case of roadblocks used in an effort to apprehend the Washington-area sniper immediately following a shooting, neither a warrant nor probable cause was required to stop vehicles at sniper roadblocks, whether they temporarily detained all cars or only white vans, which was widely believed to be a characteristics of the sniper's vehicle. The article further concludes, however, that although all-vehicles checkpoints are permissible, suspicionless searches of vehicles detained at those check points are not. On the other hand, in the seminal case of United States v. United States District Court, 407 U.S. 297, 322 (1972), the U.S. Supreme Court recognized the distinction between domestic terrorism and ordinary crime. When police have reason to believe, as they arguably did in the serial sniper case, that domestic terrorism is involved, the degree of probable cause necessary to support searches of cars stopped at checkpoints may be appropriately reduced. This is already the case with foreign-intelligence searches. Every State supreme court that has considered the issue has upheld the use of checkpoints to catch escaping suspects in the wake of serious crimes, usually by applying a balancing test that compares the limited scope of the invasion to the magnitude of the governmental interest at stake. Thus, when serious crimes by persistently dangerous criminals are involved, roadblock checkpoints are constitutional and can involve a lower threshold for probable cause for a vehicle search when domestic terrorism is reasonably suspected.