The power of the university to attest constables was granted by the Universities Act 1825, making the University Police among the oldest police forces in the United Kingdom. As a non-Home Office police service, the Chancellor and Vice-Chancellor of the University have the power to appoint constables (or in their absence any pro vice chancellor or deputy vice chancellor), which are in practice appointed and managed by the university's Proctor's Office. The Act states that these officers, once appointed, will have all the "powers and authorities, privileges, immunities, and advantages as any constables hath or shall have within his constablewick", within a 4 mile radius of the precincts of the university. However, it is stated on the Cambridge University website that they have jurisdiction within a 5 mile radius of Great St Mary's church.
Until the 1960s the Proctors and the Constabulary conducted regular street-patrols within the University precincts. Nowadays they operate on a reactive basis when disorder or demonstrations are expected. Generally the constables restrict themselves to internal university matters with all serious crime/incidents being referred to the Cambridgeshire Constabulary, who are the territorial police force responsible for the whole of Cambridgeshire.