Effects of Maryland's law banning Saturday night special handguns on crime guns.

OBJECTIVES To determine the effects of a 1988 Maryland law that banned "Saturday night special" handguns on the types of guns used in crime. To determine if controls on the lawful market for handguns affect the illegal market as well. SETTING Baltimore, Maryland, and 15 other US cities participating in a crime gun tracing project. METHODS Cross sectional comparison of the proportion of crime guns that are banned by the Maryland law, comparing Baltimore, MD with 15 other cities outside of Maryland. Multivariate linear regression analysis to determine if observed differences between Baltimore and 15 other cities are explained by demographic or regional differences among the cities rather than Maryland's law. RESULTS Among crime guns, a gun banned by Maryland's law is more than twice as likely (relative risk (RR) 2.3, 95% confidence interval (CI) 2.0 to 2.5) to be the subject of a crime gun trace request in 15 other cities combined, than in Baltimore. Among homicide guns, a crime especially relevant for public safety, a comparable difference (RR 2.1, 95% CI 1.1 to 4.2) was observed. The proportion of Baltimore's crime guns that are banned is 12 percentage points lower than would be expected based on its demographic and regional characteristics alone. Among crime guns purchased after 1990, a much smaller proportion in Baltimore are banned models than in 15 other cities. CONCLUSIONS Maryland's law has reduced the use of banned Saturday night specials by criminals in Baltimore. Contrary to the claims of some opponents of gun control laws, regulation of the lawful market for firearms can also affect criminals.