Prior to the establishment of the CPS three basic categories of criminal justice systems operated throughout the country: counties with their own Prosecuting Solicitors' Departments, counties which used local solicitors to prosecute, and the system in London which relied heavily on police officer advocates. Before the 1986 Act, police powers had also not been uniform throughout the country with some jurisdictions providing extensive police authority through by-laws. The introduction of an independent prosecution service would provide a counterbalance to extending police powers and prevent weak cases from reaching the courts. The CPS reviewed every criminal case against two principles: the need for sufficient evidence and the need to satisfy public interest demands. In the first two and one-half years of operation, the CPS stopped 5 percent of cases in London alone and 7.8 percent of cases nationwide. Underfunding and adverse reaction from other agencies are two of the primary problems that the CPS has faced.