Gun laws often restrict the place and manner in which firearms may be used. However, these laws may deter only a limited amount of gun violence, because the police are limited in their ability to prevent firearm violence or to detect violators. Laws to increase the penalties for firearm violence are a questionable deterrent, given the existing strong penalties and the frequency with which light punishments are given. Prohibiting certain groups like drug addicts and mental patients from owning guns could not be easily or effectively accomplished, and a permissive approach to licensing -- requiring a license to a waiting period -- will not reduce the number of guns in circulation. Gun registration is costly, and restricting handgun ownership to those with special needs for it would probably not eliminate illegal handguns. Thus, the central questions are whether any law can reduce the numbers of guns enough to reduce gun violence, how long it would take, and what the costs would be. Any gun control law would be an experiment with unknown effects, given the large number of guns in circulation and the strong pressure to keep them there. 2 references.