Computer Misuse Act 1990 The act that criminalized hacking in the UK by creating two new offenses and that created the offense of unauthorized modification of computer material. The basic hacking offense in Section 1 of the Act is “unauthorized access to computer material” and a person is guilty of this offense “if he causes a computer to perform any function with intent to secure access to any program or data held in any computer” knowing at the time that the access is unauthorized (see access def. 2). The intent a person has to have need not be directed at any particular program or data. This offense is targeted at computer hackers who simply gain access to see what information the computer holds without the intention to commit any other serious act. However the offense is so widely drafted that it could cover unauthorized driving of a motor car with a microprocessor-controlled ignition, unauthorized making of telephone calls from a computerized PBX, and unauthorized use of a microprocessor-controlled washing machine. The maximum penalty under Section 1 is six months imprisonment.

Section 2 of the Act creates the second hacking offense: unauthorized access with intent to commit or facilitate the commission of further offenses. It does not matter if the further offense is committed at the time of the hack or on a later occasion. The maximum penalty under Section 2 is five years imprisonment.

Section 3 of the Act provides that an offense will be committed by a person who, acting with intent, causes an unauthorized modification of the contents of any computer. The term modification is defined in Section 17 to include the addition of data or its alteration or erasure. A modification will be regarded as unauthorized if the person causing it is not authorized so to act or does not possess the consent of a person who is so entitled.