Computer Misuse Act 1990

JurisdictionUK Non-devolved
Citation1990 c. 18


Computer Misuse Act 1990

1990 CHAPTER 18

An Act to make provision for securing computer material against unauthorised access or modification; and for connected purposes.

[29th June 1990]

Be it enacted by the Queen's most Excellent Majesty, by and with the advice and consent of the Lords Spiritual and Temporal, and Commons, in this present Parliament assembled, and by the authority of the same, as follows:—

Computer misuse offences

Computer misuse offences

S-1 Unauthorised access to computer material.

1 Unauthorised access to computer material.

(1) A person is guilty of an offence if—

(a) he causes a computer to perform any function with intent to secure access to any program or data held in any computer;

(b) the access he intends to secure is unauthorised; and

(c) he knows at the time when he causes the computer to perform the function that that is the case.

(2) The intent a person has to have to commit an offence under this section need not be directed at—

(a) any particular program or data;

(b) a program or data of any particular kind; or

(c) a program or data held in any particular computer.

(3) A person guilty of an offence under this section shall be liable on summary conviction to imprisonment for a term not exceeding six months or to a fine not exceeding level 5 on the standard scale or to both.

S-2 Unauthorised access with intent to commit or facilitate commission of further offences.

2 Unauthorised access with intent to commit or facilitate commission of further offences.

(1) A person is guilty of an offence under this section if he commits an offence under section 1 above (‘the unauthorised access offence’) with intent—

(a) to commit an offence to which this section applies; or

(b) to facilitate the commission of such an offence (whether by himself or by any other person);

and the offence he intends to commit or facilitate is referred to below in this section as the further offence.

(2) This section applies to offences—

(a) for which the sentence is fixed by law; or

(b) for which a person of twenty-one years of age or over (not previously convicted) may be sentenced to imprisonment for a term of five years (or, in England and Wales, might be so sentenced but for the restrictions imposed by section 33 of the Magistrates' Courts Act 1980 ).

(3) It is immaterial for the purposes of this section whether the further offence is to be committed on the same occasion as the unauthorised access offence or on any future occasion.

(4) A person may be guilty of an offence under this section even though the facts are such that the commission of the further offence is impossible.

(5) A person guilty of an offence under this section shall be liable—

(a) on summary conviction, to imprisonment for a term not exceeding six months or to a fine not exceeding the statutory maximum or to both; and

(b) on conviction on indictment, to imprisonment for a term not exceeding five years or to a fine or to both.

S-3 Unauthorised modification of computer material.

3 Unauthorised modification of computer material.

(1) A person is guilty of an offence if—

(a) he does any act which causes an unauthorised modification of the contents of any computer; and

(b) at the time when he does the act he has the requisite intent and the requisite knowledge.

(2) For the purposes of subsection (1)(b) above the requisite intent is an intent to cause a modification of the contents of any computer and by so doing—

(a) to impair the operation of any computer;

(b) to prevent or hinder access to any program or data held in any computer; or

(c) to impair the operation of any such program or the reliability of any such data.

(3) The intent need not be directed at—

(a) any particular computer;

(b) any particular program or data or a program or data of any particular kind; or

(c) any particular modification or a modification of any particular kind.

(4) For the purposes of subsection (1)(b) above the requisite knowledge is knowledge that any modification he intends to cause is unauthorised.

(5) It is immaterial for the purposes of this section whether an unauthorised modification or any intended effect of it of a kind mentioned in subsection (2) above is, or is intended to be, permanent or merely temporary.

(6) For the purposes of the Criminal Damage Act 1971 a modification of the contents of a computer shall not be regarded as damaging any computer or computer storage medium unless its effect on that computer or computer storage medium impairs its physical condition.

(7) A person guilty of an offence under this section shall be liable—

(a) on summary conviction, to imprisonment for a term not exceeding six months or to a fine not exceeding the statutory maximum or to both; and

(b) on conviction on indictment, to imprisonment for a term not exceeding five years or to a fine or to both.

Jurisdiction

Jurisdiction

S-4 Territorial scope of offences under this Act.

4 Territorial scope of offences under this Act.

(1) Except as provided below in this section, it is immaterial for the purposes of any offence under section 1 or 3 above—

(a) whether any act or other event proof of which is required for conviction of the offence occurred in the home country concerned; or

(b) whether the accused was in the home country concerned at the time of any such act or event.

(2) Subject to subsection (3) below, in the case of such an offence at least one significant link with domestic jurisdiction must exist in the circumstances of the case for the offence to be committed.

(3) There is no need for any such link to exist for the commission of an offence under section 1 above to be established in proof of an allegation to that effect in proceedings for an offence under section 2 above.

(4) Subject to section 8 below, where—

(a) any such link does in fact exist in the case of an offence under section 1 above; and

(b) commission of that offence is alleged in proceedings for an offence under section 2 above;

section 2 above shall apply as if anything the accused intended to do or facilitate in any place outside the home country concerned which would be an offence to which section 2 applies if it took place in the home country concerned were the offence in question.

(5) This section is without prejudice to any jurisdiction exercisable by a court in Scotland apart from this section.

(6) References in this Act to the home country concerned are references—

(a) in the application of this Act to England and Wales, to England and Wales;

(b) in the application of this Act to Scotland, to Scotland; and

(c) in the application of this Act to Northern Ireland, to Northern Ireland.

S-5 Significant links with domestic jurisdiction.

5 Significant links with domestic jurisdiction.

(1) The following provisions of this section apply for the interpretation of section 4 above.

(2) In relation to an offence under section 1, either of the following is a significant link with domestic jurisdiction—

(a) that the accused was in the home country concerned at the time when he did the act which caused the computer to perform the function; or

(b) that any computer containing any program or data to which the accused secured or intended to secure unauthorised access by doing that act was in the home country concerned at that time.

(3) In relation to an offence under section 3, either of the following is a significant link with domestic jurisdiction—

(a) that the accused was in the home country concerned at the time when he did the act which caused the unauthorised modification; or

(b) that the unauthorised modification took place in the home country concerned.

S-6 Territorial scope of inchoate offences related to offences under this Act.

6 Territorial scope of inchoate offences related to offences under this Act.

(1) On a charge of conspiracy to commit an offence under this Act the following questions are immaterial to the accused's guilt—

(a) the question where any person became a party to the conspiracy; and

(b) the question whether any act, omission or other event occurred in the home country concerned.

(2) On a charge of attempting to commit an offence under section 3 above the following questions are immaterial to the accused's guilt—

(a) the question where the attempt was made; and

(b) the question whether it had an effect in the home country concerned.

(3) On a charge of incitement to commit an offence under this Act the question where the incitement took place is immaterial to the accused's guilt.

(4) This section does not extend to Scotland.

S-7 Territorial scope of inchoate offences related to offences under external law corresponding to offences under this Act.

7 Territorial scope of inchoate offences related to offences under external law corresponding to offences under this Act.

(1) The following subsections shall be inserted after subsection (1) of section 1 of the Criminal Law Act 1977

(1A) Subject to section 8 of the Computer Misuse Act 1990 (relevance of external law), if this subsection applies to an agreement, this Part of this Act has effect in relation to it as it has effect in relation to an agreement falling within subsection (1) above.

(1B) Subsection...

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