272.This section sets out the extra tests to be fulfilled if a key is required to be disclosed rather than the disclosure of protected information in an intelligible form.
273.Subsection (1) states that a notice may not contain a statement that it can be complied with only by disclosing a key unless a direction to this effect has been given by the person giving permission for the notice to be served.
274.The effect of Subsections (2) and (3) is that a direction that a key must be disclosed given by the police, HM Customs and HM Forces must be given expressly by a person of the rank set out in this subsection (namely, Chief Officer of police or equivalent).
275.Subsection (4) provides that a person may only give a direction requiring the disclosure of a key if he believes that there are special circumstances to the case making this necessary; and that giving such a direction is proportionate to what is sought to be achieved by doing so.
276.Subsection (5) specifies that in deciding whether it is proportionate to require that a key be disclosed, consideration must be given to the sort of other information also protected by the key in question and any potential adverse impact on a business that might result from requiring that a key be disclosed.
277.The effect of Subsections (6) and (7) is that any direction to disclose a key given internally by the police, HM Customs or HM Forces must be notified, within 7 days, to the Intelligence Services Commissioner or the Chief Surveillance Commissioner, as appropriate.
Other Authorisations Part Iii:  Investigation of Electronic Data Protected by Encryption Etc Section 51: Cases in which key required