Seizure of computer evidence

In this edition consideration will be given to the seizure of evidence contained in computers.

Special provision is made for the seizure of information contained in computers. The phrase ‘contained in a computer’ must be read as including information stored on disc or tape which is not stored in the computer but is only accessible through the medium of a computer. Any other interpretation would exclude so much material as to render the provision virtually useless. It follows that the constable can seize a computer disc or tape or, if he only requires specific information which is on the disc or tape, a print-out of the relevant part (S.19(4), 20, Police and Criminal Evidence Act 1984).

However, the ease with which information can be concealed within a computer (eg. by the use of trigger words before access is allowed) and the possibility that the computer on the premises is merely a local terminal for a central database held elsewhere mean that specialist officers will be needed to conduct the search, and that frequently a complete tape must be studied or taken away. Such officers will need to study the operating manual which governs the computer and to interview the computer controller and/or programmer. Section 20 extends the S.19(4) provision to all powers of seizure contained in any statutory provision passed or made before or after the 1984 Act and to the powers of seizure under S.8 and 18 and to the power of seizure when executing a warrant to search for and seize excluded or special procedure material contained in para 13 of Sch 1 to the 1984 Act. Thus, whenever there is a statutory power to seize material, there is a statutory power to require a print-out of computerised information which has been obtained in consequence of an offence or, more usually, which is evidence of an offence, eg a constable executing a warrant under the Obscene Publications Act 1959 may, having seized obscene material, require a print-out of information contained in a computer about the source of the supply of such material.

The Computer Misuse Act 1990, S.1, makes unauthorised access to computer material an offence. Section 10 of that Act provides that this offence shall not apply to the exercise of law enforcement powers. Section 162 of the Criminal Justice and Public Order Act 1994 deals with the insertion into computer programs of provisions for access only by authorised persons or a particular class of persons.

After para 10(b) the following words are added: ‘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 the said section(1)(1)‘.

In this section ‘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.

Computer evidence may or may not be hearsay. Recourse must be made to the definition of “statement” in S.115 (1) of the Criminal Justice Act 2003. Where a computer is used merely to perform functions of calculation, no question of hearsay is involved in producing evidence of what the computer “said”. For example there is no difficulty with producing a printout from an Intoximeter that has performed an analysis of specimens of breath which is admissible as non-hearsay evidence.

Where a computer is used to record information that is supplied by a person, the hearsay rule will come into play if it is sought to produce a printout from the computer to prove that what the person said was true. Thus documentary records stored on computers are hearsay, see Coventry Justices, ex parte Bullard(1992) 95 Cr App R 175 in which it was held that the crucial distinction was between computer “p