Although Britian does not have a national police force, the Government exerts influence over the police through regular circulars on aspects of policing issued from the Home Office to chiefs of police, through a research unit that examines new technology and evaluates programs to be implemented by local forces, and through a training academy for senior officers of forces throughout the Nation. Regional activities are supportive of local forces and include recruit training, forensic laboratory work, and regional crime squads. The degree of centralization in a given police force depends on the police chief's philosophy. An emphasis on proactive or preventive policing tends to produce a decentralized force, while a focus on reactive policing favors a centralized structure. At the division level, centralization occurs on two fronts. On the administrative front, decisions regarding the prosecution of offenders and the presentation of cases for court are made at the divisional level. On the operational front, supportive units, such as fingerprint offices and crime prevention offices, are based at divisional headquarters. At the subdivision level, certain tasks, such as uniform patrol work and criminal investigation work, are centralized, in that assignments are given from a central office. Community constables, however, can select, within a broad framework, their own duty hours. They are given considerable latitude in their selection of work or projects they feel are best suited to the needs of the areas they serve. A table is included.