English law does not directly recognise terms of art such as hacking, cracking, and tapping.
Such activities thereby have to be fitted into legal definitions before a prosecution can be brought under criminal law or a private action brought under civil law.
This blogpost sets out some of the potentially applicable law relating to the unauthorised interception and retrieval of voice messages.
Section 48 of Wireless Telegraphy Act 2006
Under section 48 of the Wireless Telegraphy Act 2006 (WTA), a person commits an offence if (unless authorised) they use “wireless telegraphy apparatus” (which may include a mobile telephone) with the intent to obtain information as to the contents, sender or addressee of a message of which neither they nor a person on whose behalf they is acting is an intended recipient.
It is also an offence if they disclose information as to the contents, sender or addressee of such a message. (This would thereby presumably include publication of such a message in a newspaper.)
Note this offence does not need an interception to actually have occurred; it is enough that they used a mobile with that intent, or that they disclosed the wrongfully retrieved message to another person.
The Crown Prosecution Service (CPS) guidance is here.
This offence only took effect on 8 February 2007 and so cannot be used for any incident before that date.
Sections 1 and 2 of Regulation of Investigatory Powers Act 2000
The Regulation of Investigatory Powers Act 2000 (RIPA) provides that it is both a criminal offence and a tort (a civil right of action) to unlawfully interfere with any communication in the course of transmission.
The offences are provided for in sub-section 1(1)(b) (public telecommunications systems) and sub-section 1(2) (private telecommunications systems), and the tort is provided for in sub-section 1(3).
By virtue of sub-sections 2(7) and 2(8) of RIPA, the tort and the offences contained in RIPA include interception of voicemails.
The CPS guidance is here.
Section 1 of the Computer Misuse Act 1990
The Computer Misuse Act (CMA) provides under section 1 that it is an offence if a person causes a computer to perform any function with intent to secure access to any program or data held in any computer when the access he intends to secure is unauthorised, and that person knows at the time when he causes the computer to perform the function that that is the case.
The question is whether the data is being held on a "computer". There is no definition of computer in CMA, but either the handset or the mobile operator's server and voicemail storage and retrieval system is likely to be a computer for the purposes of CMA.
The law blogger Simon Bradshaw, a lawyer and electronics engineer (who also helped pro bono on the Simon Singh case), has written about what is a computer under CMA here.
The CPS guidance is here.
Other legal areas
Also applicable may be law relating to misuse of personal information (which is a tort which has recently developed by the Courts out of the historic equitable doctrine of confidentiality) and provisions of the Data Protection Act 1998.
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