Computer Misuse Act 1990 is reproduced under the terms of Crown Copyright
Policy Guidance issued by HMSO. The text is taken from the 4th Impression of
January 1997.
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Computer Misuse Act 1990

ARRANGEMENT OF SECTIONS

Computer misuse offences
1. [2]Unauthorised access to computer material.
2. [3]Unauthorised access with intent to commit or facilitate commission of
further offences.
3. [4]Unauthorised modification of computer material.
Jurisdiction
4. [5]Territorial scope of offences under this Act.
5. [6]Significant links with domestic jurisdiction.
6. [7]Territorial scope of inchoate offences related to offences under this
Act.
7. [8]Territorial scope of inchoate offences related to offences under
external law corresponding to offences under this Act.
8. [9]Relevance of external law.
9. [10]British citizenship immaterial.
Miscellaneous and general
10. [11]Saving for certain law enforcement powers.
11. [12]Proceedings for offences under section 1.
12. [13]Conviction of an offence under section 1 in proceedings for an
offence under section 2 or 3.
13. [14]Proceedings in Scotland.
14. [15]Search warrants for offences under section 1.
15. [16]Extradition where Schedule I to the Extradition Act 1989 applies.
16. [17]Application to Northern Ireland.
17. [18]Interpretation.
18. [19]Citation, commencement etc.
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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

Unauthorised access to computer material. 1.-(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.

Unauthorised access with intent to commit or facilitate commission of
further offences. 2.-(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.
1980 c.43. (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.

Unauthorised modification of Computer material 3.-(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.
1971 c.48 (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.