PST's main activity is operational policing. Carrying out analyses and compiling reports are important support functions. PST's activities entail the prevention and investigation of offences. Guidelines are drawn up by the Norwegian Parliament covering the types of offences which PST is to combat. The Ministry of Justice expands on these regularly.
The statutory basis for PST's major areas of work is Chapter IIIA of the Police Act (Act no. 53 of 4 August 1995 concerning the police). Section 17 b of the Police Act stipulates that PST shall prevent and investigate
- offences against the Penal Code Chapters 8 (crimes against the security and independence of the State) and 9 (crimes against the Norwegian constitution and head of state), the Defence Secrets Act and the Security Act,
- illegal intelligence activity,
- proliferation of weapons of mass destruction and of equipment, material and technology that facilitate the production or use of such weapons,
- offences against provisions in or pursuant to the Act relating to control of the export of strategic goods, services and technology, etc. and the Act relating to the implementation of binding resolutions of the United Nations Security Council or other legislation relating to similarly special measures, and
- sabotage or politically motivated violence or coercion, or offences against sections 147 a and 147 b of the Penal Code.
Section 17 c of the Police Act stipulates further that The Norwegian Police Security Service's Headquarters shall:
- prepare threat assessments for the political authorities,
- co-operate with foreign police, security and intelligence services, and
- carry out checks on individuals for use in security vetting.