Following the War of 1812, the British ceased to control American commerce and Boston began to develop rapidly. Social classes became more stratified, with a highly visible aristocracy. The city also became politically polarized and religiously divided. Social structures and institutions established when Boston was a colony were no longer sufficient to deal with the problems brought on by rapid economic and social change. In an attempt to respond to current needs, the Municipal Court redefined its mission by adding regulatory disputes and diverting minor cases into extra-legal channels. The role of the Police Court was also expanded, as it assumed jurisdiction over minor regulatory disputes and minor vice. The bar association also took steps to increase the professional training and standards of lawyers and judges. The role of the prosecutor also expanded in three distinct directions: (1) dismissing minor cases before they reached the grand jury; (2) issuing informal probation to minor offenders; and (3) plea bargaining. Finally, the author notes the increase in crime in various quarters, particularly juvenile crime and crime committed by Irish immigrants, who were arriving in Boston in record numbers. 45 notes, 42 figures, 49 tables, 139 references