Civil rights and civil liberties groups are increasingly challenging the growing firepower and violent tactics of SWAT units. Civil libertarians accuse the units of engaging in paramilitary tactics that often slight or outright violate the civil rights of citizens. They also fear that the units are eroding the important separation between domestic law enforcement and the military. The effectiveness of the units is another issue in debate. Some experts say the units escalate rather than defuse high-risk situations. Defenders of SWAT insist that well-armed criminal elements warrant special tactics and weapons. The history and scope of SWAT units are reviewed, the extent of military training of the units is examined, and examples unit operations are cited. 6 photographs