Legalize / United Kingdom / Public General Act

Computer Misuse Act 1990

Type Public General Act

Publication 1990-06-29

State In force

Department Statute Law Database

Source legislation.gov.uk

Reform history JSON API

Computer misuse offences

Unauthorised access to computer material

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(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 , or to enable any such access to be secured;

(b) the access he intends to secure , or to enable to be secured, is unauthorised; and

(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

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

(a) on summary conviction in England and Wales, to imprisonment for a term not exceeding the general limit in a magistrates’ court or to a fine not exceeding the statutory maximum or to both;

(b) on summary conviction in Scotland, to imprisonment for a term not exceeding 12 months or to a fine not exceeding the statutory maximum or to both;

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

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(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 who has attained the age of twenty-one years (eighteen in relation to England and Wales) and has no previous convictions 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 in England and Wales, to imprisonment for a term not exceeding the general limit in a magistrates’ court or to a fine not exceeding the statutory maximum or to both;

(b) on summary conviction in Scotland, to imprisonment for a term not exceeding 12 months or to a fine not exceeding the statutory maximum or to both;

Unauthorised modification of computer material

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

(a) he does any unauthorised act in relation to a computer;

(b) at the time when he does the act he knows that it is unauthorised; and

(2) This subsection applies if the person intends by doing the act—

(a) to impair the operation of any computer;

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

(d) to enable any of the things mentioned in paragraphs (a) to (c) above to be done.

(3) This subsection applies if the person is reckless as to whether the act will do any of the things mentioned in paragraphs (a) to (d)to (c) of subsection (2) above.

(4) The intention referred to in subsection (2) above, or the recklessness referred to in subsection (3) above, need not relate to—

(a) any particular computer;

(b) any particular program or data; or

(5) In this section—

(a) a reference to doing an act includes a reference to causing an act to be done;

(b) “act” includes a series of acts;

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

(a) on summary conviction in England and Wales, to imprisonment for a term not exceeding the general limit in a magistrates’ court or to a fine not exceeding the statutory maximum or to both;

(b) on summary conviction in Scotland, to imprisonment for a term not exceeding 12 months or to a fine not exceeding the statutory maximum or to both;

Jurisdiction

Territorial scope of offences under this Act

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

(4A) It is immaterial for the purposes of an offence under section 3A whether the accused was in the home country concerned at the time of any act or other event proof of which is required for conviction of the offence if there is a significant link with domestic jurisdiction in relation to the offence.

(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

Significant links with domestic jurisdiction

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

(1A) In relation to an offence under section 1, 3, 3ZA or 3A, where the accused was in a country outside the United Kingdom at the time of the act constituting the offence there is a significant link with domestic jurisdiction if—

(a) the accused was a United Kingdom national at that time; and

(b) the act constituted an offence under the law of the country in which it occurred.

(1B) In subsection (1A)—

“country” includes territory;

“United Kingdom national” means an individual who is—a British citizen, a British overseas territories citizen, a British National (Overseas) or a British Overseas citizen;a person who under the British Nationality Act 1981 is a British subject; ora British protected person within the meaning of that Act.

(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.

(b) that any computer containing any program or data to which the accused by doing that act secured or intended to secure unauthorised access, or enabled or intended to enable unauthorised access to be secured, 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 unauthorised act (or caused it to be done) ; or

(b) that the unauthorised act was done in relation to a computer in the home country concerned.

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

(a) that the accused was in the home country concerned at the time when he did the unauthorised act (or caused it to be done);

(b) that the unauthorised act was done in relation to a computer in the home country concerned;

(c) that the unauthorised act caused, or created a significant risk of, serious damage of a material kind (within the meaning of that section) in the home country concerned.

Territorial scope of inchoate offences related to offences under this Act

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(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 this Act 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) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(4) This section does not extend to Scotland.

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

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(1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(3) The following subsections shall be inserted after section 1(1) of the Criminal Attempts Act 1981—

(1A) Subject to section 8 of the Computer Misuse Act 1990 (relevance of external law), if this subsection applies to an act, what the person doing it had in view shall be treated as an offence to which this section applies. (1B) Subsection (1A) above applies to an act if— (a) it is done in England and Wales; and (b) it would fall within subsection (1) above as more than merely preparatory to the commission of an offence under section 3 of the Computer Misuse Act 1990 but for the fact that the offence, if completed, would not be an offence triable in England and Wales.

(4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Relevance of external law

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(1) A person is guilty of an offence triable by virtue of section 4(4) above only if what he intended to do or facilitate would involve the commission of an offence under the law in force where the whole or any part of it was intended to take place.

(2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(3) A person is guilty of an offence triable by virtue of section 1(1A) of the Criminal Attempts Act 1981 . . . only if what he had in view would involve the commission of an offence under the law in force where the whole or any part of it was intended to take place.

(4) Conduct punishable under the law in force in any place is an offence under that law for the purposes of this section, however it is described in that law.

(5) Subject to subsection (7) below, a condition specified in subsection (1) or (3) above shall be taken to be satisfied unless not later than rules of court may provide the defence serve on the prosecution a notice—

(a) stating that, on the facts as alleged with respect to the relevant conduct, the condition is not in their opinion satisfied;

(b) showing their grounds for that opinion; and

(6) In subsection (5) above “the relevant conduct” means—

(a) where the condition in subsection (1) above is in question, what the accused intended to do or facilitate;

(b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(7) The court, if it thinks fit, may permit the defence to require the prosecution to show that the condition is satisfied without the prior service of a notice under subsection (5) above.

(8) If by virtue of subsection (7) above a court of solemn jurisdiction in Scotland permits the defence to require the prosecution to show that the condition is satisfied, it shall be competent for the prosecution for that purpose to examine any witness or to put in evidence any production not included in the lists lodged by it.

(9) In the Crown Court the question whether the condition is satisfied shall be decided by the judge alone.

(10) In the High Court of Justiciary and in the sheriff court the question whether the condition is satisfied shall be decided by the judge or, as the case may be, the sheriff alone.

British citizenship immaterial

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(1) Except as provided by section 5(1A),In any proceedings brought in England and Wales in respect of any offence to which this section applies it is immaterial to guilt whether or not the accused was a British citizen at the time of any act, omission or other event proof of which is required for conviction of the offence.

(2) This section applies to the following offences—

(a) any offence under this Act ;

(b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(d) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Miscellaneous and general

Saving for certain law enforcement powers

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Sections 1 to 3A have effect without prejudice to the operation—in England and Wales of any enactment relating to powers of inspection, search or seizureor of any other enactment by virtue of which the conduct in question is authorised or required; andin Scotland of any enactment or rule of law relating to powers of examination, search or seizureor of any other enactment or rule of law by virtue of which the conduct in question is authorised or requiredand nothing designed to indicate a withholding of consent to access to any program or data from persons as enforcement officers shall have effect to make access unauthorised for the purposes of any of those sections. In this section— “ enactment ” means any enactment, whenever passed or made, contained in— an Act of Parliament;an Act of the Scottish Parliament;a Measure or Act of the National Assembly for Wales;an instrument made under any such Act or Measure;any other subordinate legislation (within the meaning of the Interpretation Act 1978); “ enforcement officer ” means a constable or other person charged with the duty of investigating offences; and withholding consent from a person “as” an enforcement officer of any description includes the operation, by the person entitled to control access, of rules whereby enforcement officers of that description are, as such, disqualified from membership of a class of persons who are authorised to have access.

Proceedings for offences under section 1

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Conviction of an offence under section 1 in proceedings for an offence under section 2 or 3

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Proceedings in Scotland

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(1) A sheriff shall have jurisdiction in respect of an offence under section 1 or 2 above if—

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

(b) any computer containing any program or data to which the accused by doing that act secured or intended to secure unauthorised access, or enabled or intended to enable unauthorised access to be secured, was in the sheriffdom at that time.

(2) A sheriff shall have jurisdiction in respect of an offence under section 3 above if—

(a) the accused was in the sheriffdom at the time when he did the unauthorised act (or caused it to be done) ; or

(b) the unauthorised act was done in relation to a computer in the sheriffdom.

(2A) A sheriff shall have jurisdiction in respect of an offence under section 3ZA above if—

(a) the accused was in the sheriffdom at the time when he did the unauthorised act (or caused it to be done), or

(b) the computer in relation to which the unauthorised act was done was in the sheriffdom at that time.

(2B) A sheriff shall have jurisdiction in respect of an offence under section 3A above if—

(a) the accused was in the sheriffdom at the time when—

(i) he made, adapted, supplied or offered to supply the article intending it to be used as mentioned in subsection (1) of that section,

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