 In contrast to a deterrent of punishment, a preventive police force would deter criminality by making crime cost-ineffective, anticipating the "crime doesn't pay" motto promoted by American police reformers in the 20th century.Not only would a preventive police trump punishment as a deterrent, it would also reduce the costs of a criminal justice system over-burdened by prosecuting crimes that have already been committed.In the second draft of his 1829 Police Act, the "object" of the new Metropolitan Police, was changed by Robert Peel to the "principal object", which was the "prevention of crime".