Summary Offences Act 1953

A person who—

causes (directly or indirectly) an unauthorised impairment of data held in a credit card or on a computer disk or other device used to store data by electronic means; and

knows that the impairment is unauthorised; and

intends, by that impairment, to cause harm or inconvenience, or is reckless as to whether harm or inconvenience will ensue, is guilty of an offence.

An impairment of data is unauthorised unless it is made by the owner of the data or some other person who has an authorisation or licence (express or implied) from the owner of the data to cause the impairment.

A person is to be regarded as the owner of data if—

the person brought the data into existence or stored the data in the credit card or on the computer disk or other device for his or her own purposes; or

the data was brought into existence or stored in the credit card or on the computer disk or other device at the request or on behalf of that person; or

the person has a proprietary interest in, or possessory rights over, the medium in which the data is stored entitling the person to determine what data is stored in the medium and in what form.

The onus of establishing that an impairment of data was unauthorised lies on the prosecution.