Whilst all public authorities can authorise directed surveillance, not all are empowered to use a CHIS.
Those public authorities and the ranks/grades of staff currently entitled to authorise directed surveillance or a CHIS are listed in Statutory Instrument 2010/521(under RIPA) and in Scottish Statutory Instrument 2010/350 (under RIP(S)A). More senior officers are required to authorise these tactics should they involve the acquisition of confidential information or involve the use of a juvenile or vulnerable person as a CHIS.
The grounds upon which a public authority may grant the use of such powers are determined by law and are also set out in the above Statutory Instruments. The current grounds are:
a) In the interests of national security
b) For the purpose of preventing or detecting crime or of preventing disorder
c) In the interests of the economic well-being of the UK
d) In the interests of public safety
e) For the purpose of protecting health
f) For the purpose of assessing or collecting any tax, duty, levy or other imposition, contribution or charge payable to a government department
The Secretary of State and Scottish Ministers are able to add to or amend these grounds by means of the Parliamentary process, but have not done so to date.
Certain limitations have also been imposed by The Protection of Freedoms Act 2012.