The support for mandatory penalties for carrying or possessing firearms without requisite papers rests on numerous misconceptions about restrictive firearms laws and the circumstances which affect the carrying of guns. Massachusetts is one of the jurisdictions which has enacted such legislation and in which criminologists have conducted evaluations of the impacts of the legislation. Its Bartley-Fox law, enacted in 1974, does not reduce the amount of violent crime or affect the robbery for murder rates. The law seems only to increase the number of injury-related aggravated assaults and to lessen the effectiveness of the criminal justice system's efforts with respect to career criminals. Only about 40 persons in Boston were sentenced under the law during a 2-year period, compared to about 20,000 violent crimes during the same period. In addition, the concept of mandatory penalties appears to be aimed mainly at otherwise law-abiding, nonviolent members of society who carry guns due to their fear of crime. Mandatory penalties invite police discretion, raise search and seizure issues and issues of equal protection, and will increase court caseloads as a result of a reduction in guilty pleas. Footnotes and 26 references are provided.