Computer misuse act


The growth of computer use over recent years has resulted in many operations becoming computerised, both in the work place and in everyday life. This reliance has resulted in the need for an effective legislation over them, to control crime and misuse, leading to the creation of the Computer misuse act 1990.

Overview Of The Legislation

The Computer Misuse Act 1990 protects and secures computer material against unauthorised access and any harmful type of modification. It has three offences, unauthorised access which can hold a sentence of imprisonment for six months, unauthorised access with intent to commit of facilitate commission of further offences which holds sentences of up to five years along with, unauthorised modification.

Its main purpose is to prevent copyright infringements, hacking, using computer data for fraud or blackmail, the creation of viruses and the illegal deleting or altering of computer data. The act makes the offences which can be made on computers clear making sure the ever growing amount of people using them, both victims and criminals are aware of the offences they could be subject to, in both committing and being a part of them.

Cases Related To The Legislation

R v Pile- the defendant created Pathogen and Queeg viruses, using a Polymorphic encryption engine, to conceal viruses within computer programs, and was convicted for unauthorised modification.

DPP v Bignall- Police officers obtained details relating to two motor cars from the police national computer, as this was a non police purpose it was classed as unauthorised use. However they did not commit an offence under section1therefore were acquitted.

DPP v Ellis- The defendant had used non open access computers at a university, despite warnings so the appeal was dismissed, for committing unauthorised access.

R v Feltis- Video surveillance showed a computer operator, disconnecting cables on IBM AS/400 at Thorn UK, causing a cost of damage of £500,000 to the company, and was sentenced for unauthorised modification.

Examples Of The Legislation's Importance

Preventing computer misuse in the work establishment is very important as it's very easy to become a victim. The main ways to lower your chances of being effected is to continually change passwords and make sure they are strong to lower chances of receiving viruses and Trojan horses via emails. Make sure all computers have up-to-date virus protection software. Implement restrictions on the internet to sites which can be accessed by employees and monitor what they are using them for. And finally educate employees making them aware of computer crimes they can become subject to without knowing.


Currently the computer misuse act is the only way of preventing and dealing with computer misuse in the UK so is very important legislation, in keeping the 13.9 million people in the UK who own computers, safe from unauthorised access and modification, especially when dealing with businesses where it can result in huge losses of finance.

Table Of Cases

R v Pile [1995] Plymouth Crown Court

DPP v Bignall [1998] 1 Cr. App. R. 1

DPP v Ellis [2001] EWHC Admin 362 (QBD)

R v Feltis [1996] EWCA Crim 776


Computer misuse act 1990


Lloyd, J. (2008) Information technology law, Oxford: Oxford University Press