Powers contained in RIPA 2000 and the Intelligence Services Act 1994 give agencies power to conduct what is described as ‘intrusive’ and ‘targeted’ surveillance. The terminology here is potentially confusing, given that other agency powers – such as the large-scale interception of communications and access to communications data – are often described by civil society groups as forms of ‘mass surveillance’, and the term ‘surveillance state’ is often used to describe intelligence powers in general.
Specifically, ‘intrusive surveillance’ refers to “the use of covert techniques to monitor an SoI’s movements, conversations and activities in private places including a suspect’s home or vehicle.” The Intelligence and Security Committee considers the use of this power “highly intrusive” and “used sparingly … only in support of the highest priority investigations.” Warrants for intrusive surveillance are signed by a Secretary of State and remain in force for six months, though in some cases can remain in place for several years. Warrants can be issued under RIPA, or in conjunction with authorisation for interference with property under the Intelligence Services Act 1994.
‘Directed surveillance’ is that which takes place outside of these private spaces; in essence, in public areas. Activities in this area might include tracking a subject’s movements and still or video recording of them. Warrants for directed surveillance are approved inside the agencies and are valid for three months.
 Intelligence and Security Committee, Report on Privacy and Security, 2015, p.61. Accessible at http://isc.independent.gov.uk/files/20150312_ISC_P+S+Rpt(web).pdf