8.—(1) In this Part, an authorisation for the conduct or use of a relevant source is a long term authorisation if the periods mentioned in paragraph (2)(a) and (b), when taken together, exceed 12 months.
(2) The periods are—
(a)the period for which the relevant source will be authorised under the authorisation; and
(b)subject to paragraph (4), any period or periods for which that source has previously been authorised as a source in relation to the same investigation or operation.
(3) If a relevant source has been authorised previously as a source for a period or periods totalling less than 12 months, any further authorisation, unless renewed, ceases to have effect at the end of a period of 12 months from the date of the further authorisation, less the total period of any previous authorisation (and section 19(3)(b) of the Act has effect as if the period specified there were modified accordingly).
(4) When calculating the previous authorisation periods mentioned in paragraph (2)(b) or (3), the following are not to be taken into account—
(a)any period for which the relevant source has been authorised as a source if that authorisation was granted orally or by a person whose entitlement to authorise is confined to urgent cases;
(b)any authorisation of that source which ceased to have effect more than 3 years before the intended commencement date of the authorisation being notified under this Part; and
(c)any period for which that source was authorised prior to 2nd February 2015 under an authorisation which is not in effect on that date.
(5) If an authorisation for the conduct or use of a relevant source is an authorisation to which Part 2 applies, the references in paragraphs (1) and (3) to 12 months are to be read as if they were references to 3 months.