The Computer Misuse Act of 1990 (CMA) (chapter 18) is the primary law regarding computer crimes in the U.K. It outlaws the unauthorized modification of data stored or transmitted by IT systems, as well as unauthorized access to such systems. It was amended through the Police and Justice Act 2006.
The Act remains the primary piece of U.K. legislation focusing on the misuse of computer systems. It covers crimes such as hacking and the deliberate spread of viruses, and was created to prevent unauthorized access to or modification of computer systems and to deter criminal elements from using a computer to assist in the commission of a criminal offense or from impairing or hindering access to data stored in a computer.