Computer Generated Evidence In CourtIntroductionWe are living in what is usually described as an ‘information society’ and asthe business community makes ever greater use of computers the courts are goingto find that increasingly the disputes before them turn on evidence which has atsome stage passed through or been processed by a computer. In order to keep instep with this practice it is vital that the courts are able to take account ofsuch evidence. As the Criminal Law Revision Committee recognised, ‘theincreasing use of computers by the Post Office, local authorities, banks andbusiness firms to store information will make it more difficult to prove certainmatters such as cheque card frauds, unless it is possible for this to be donefrom computers’ (CLRC 1972, para 259).
AdmissibilityThe law of evidence is concerned with the means of proving the facts which arein issue and this necessarily involves the adduction of evidence which is thenpresented to the court. The law admits evidence only if it complies with therules governing admissibility.
Computer output is only admissible in evidencewhere special conditions are satisfied. These conditions are set out in detailin section 69 of the Police and Criminal Evidence Act (PACE) 1984 (see furtherNyssens 1993, Reed 1993 and Tapper 1993).
In general the principles of admissibility are that the evidence must berelevant to the proof of a fact in issue, to the credibility of a witness or tothe reliability of other evidence, and the evidence must not be inadmissible byvirtue of some particular rule of law (Keane 1994, pp 15-20; Tapper 1990, pp 51-61).
Real evidence usually takes the form of some material object (including computeroutput) produced for inspection in order that the court may draw an inferencefrom its own observation as to the existence, condition or value of the objectin question. Although real evidence may be extremely valuable as a means ofproof, little if any weight attaches to it unless accompanied by testimony whichidentifies the object in question and explains its connection with, orsignificance in relation to, the facts in issue or relevant to the issue.
This is illustrated in the case of R v Wood (1982) 76 Cr App R 23 where theappellant was convicted of handling stolen metals. In order to prove that metalfound in his possession and metal retained from the stolen consignment had thesame chemical composition cross-checking was undertaken and the figures producedwere subjected to a laborious mathematical process in order that the percentageof the various metals in the samples could be stated as figures. This was doneby a computer operated by chemists. At the trial, detailed evidence was given asto how the computer had been programmed and used. The computer printout was nottreated as hearsay but rather as real evidence, the actual proof and relevanceof which depended upon the evidence of the chemists, computer programmer andother experts involved.
The difficulty in the application of this rule lies in its interaction with thehearsay rule. Evidence is hearsay where a statement in court repeats a statementmade out of court in order to prove the truth of the content of the out of courtstatement (Sparks v R 1964 AC 964). Similarly evidence contained in a documentis hearsay if the document is produced to prove that statements made in courtare true (Myers v DPP 1965 AC 1001). The evidence is excluded because thecrucial aspect of the evidence, the truth of the out of court statement (oral ordocumentary), cannot be tested by cross-examination. (1) The problem, however,occurs because some statements, although in form assertive and inadmissible ifthey were to originate in the minds of human beings, in fact originate in somepurely mechanical function of a machine and can be used circumstantially toprove what they appear to assert.
The basis for this view was laid down in a case having little to do withcomputers. In the Statute of Liberty 1968 2 All ER 195 a collision occurredbetween two vessels on the Thames estuary. The estuary was monitored by radarand a film of the radar traces was admitted into evidence. Simon P rejected theargument that the film was hearsay – he held that it constituted real evidenceand not hearsay and he placed it on a par with direct oral testimony. Wheremachines have replaced human beings, it makes no sense to insist upon rulesdevised to cater for human beings but rather, as Simon P said ‘the law is boundthese days to take cognisance of the fact that mechanical means replace humaneffort’ (at p 196).
This useful distinction was apparently overlooked in R v Pettigrew (1980) 71 CrApp R 39 where the prosecution wished to prove that some bank notes found in thepossession of the accused were part of a particular consignment despatched bythe Bank of England. A computer printout was used to prove this but the Court ofAppeal held that such evidence was inadmissible under the statutory provisionconcerned (section 1 Criminal Evidence Act 1965 – now repealed). The Court tookthe view that the operator did not have the requisite personal knowledge of thenumbers of the bank notes rejected from the machine since they were compiledcompletely automatically by the computer. This conclusion is quite accurate anda perfect application of the hearsay rule but it failed to consider the use ofthe print-out as real evidence. This confusion between hearsay and real evidenceis unfortunate and it may explain why it was necessary to create special rulesfor computer evidence.
Criminal ProceedingsIt is imperative that computer output should be readily used as evidence incriminal cases since otherwise many cases, particularly those involvingdishonesty, would be immune from prosecution. At the same time one cannot be toocomplacent about the technology since computers are not infallible. It is widelyacknowledged that ‘hacking’ and ‘viruses’ may affect information stored on acomputer. These factors were obviously taken into consideration when enactingthe provisions governing computer generated evidence in criminal proceedings.
(2)Section 69 of the Police and Criminal Evidence Act 1984 provides that:”(1) In any proceedings, a statement in a document produced by a computer shallnot be admissible as evidence of any fact therein unless it is shown-(a) that there are no reasonable grounds for believing that the statement isinaccurate because of improper use of the computer and;(b) that at all materials times the computer was operating properly or, if not,that any respect in which it was not operating properly or was out of operationwas not such as to affect the production of the document or the accuracy of itscontents.”In addition any rules of court made under section 69(2) must also be satisfied(at the time of writing no such rules have been made).
Real evidence and hearsaySo far the discussion has focused on exceptions to the hearsay rule. Howeverevidence derived from a computer constitutes real or direct evidence when it isused circumstantially rather than testimonially, that is to say when the factthat it takes one form rather than another makes it relevant, rather than thetruth of some assertion which it contains. (3)Direct evidence produced by a computer is not subject to the hearsay rule. As wehave already noted, in R v Wood calculations were carried out by a computerspecifically for the purpose of the trial to verify whether the composition ofstolen metals matched original metals. Computer output was admissible as realevidence since it did not purport to reproduce any human assertion which hadbeen entered into it. It was held that the machine was a tool and that in theabsence of any evidence that it was defective, the printout, the product of amechanical device, fell into the category of real evidence. The court didrecognise, however, that the dividing line between admissibility of computergenerated evidence as real evidence or hearsay would not always be easy to draw.
The same distinction and result were reached in Castle v Cross 1985 1 All ER87 and in R v Spiby (1990) 91 Cr App R 186, CA an automatic telephone loggingcomputer which logged the call details without human intervention was admittedas real evidence. The Court also held that, in the absence of evidence to thecontrary, courts would presume that such a computer was in working order at thematerial time.
Thus as far as the common law is concerned the status of computer evidence asreal or hearsay will depend, in each case, on the content of the computer record,the reason for using it in evidence and the way in which it was compiled. Caseslike R v Wood and R v Spiby, however, must now be read in light of the decisionsin R v Shephard 1993 1 All ER 225, HL and R v Cochrane 1993 Crim LR 48, CA.
In R v Shephard the House of Lords held that section 69 PACE 1984 imposes a dutyon anyone who wishes to admit a statement in a document produced by a computerto produce evidence that will establish that it is safe to rely on the document;such a duty cannot be discharged without evidence by the application of thepresumption that the computer is working correctly expressed in the maxim omniapraesumuntur rite esse acta; and it makes no difference whether the statement isor is not hearsay. In R v Cochrane it was held that before the judge can decidewhether computer printouts are admissible, whether as real evidence or ashearsay, it is necessary to call appropriate authoritative evidence to describethe function and operation of the computer. In that case the prosecution wantedto prove that certain cash withdrawals were made from a particular ‘cashpoint’.
The machine would only dispense money if the correct Personal Identity Numberwas entered. The matching was carried out by a mainframe computer and evidenceof its proper functioning was thus required by the court. The prosecution didnot adduce this evidence and the conviction was set aside on appeal.
As we have seen, a printout from a computer which has been used as a calculatingdevice, or which records information automatically without human intervention,is admissible as real evidence and involves no question of hearsay. (4) On theother hand, where the printout contains information supplied to the computer bya person, it is hearsay if tendered for the truth of what is asserted, but maybe admissible under either sections 23 or 24 of the Criminal Justice Act 1988. Astatement can only be admitted under sections 23 or s 24 if its maker (or theoriginal supplier) had (or may reasonably be supposed to have had) personalknowledge of the matters dealt with. Furthermore, under section 24 the ‘creator’of the document must have been acting in the course of a trade or business etc.
A statement in a computer printout which has satisfied the foundationrequirements of sections 23 or 24 can only be admitted on satisfaction of theadditional requirements contained in section 69. (5)Section 69 is couched in negative terms making it clear that evidence which doesnot satisfy its requirements is inadmissible. The object of section 69 is toimpose a duty on anyone who wishes to introduce a document produced by acomputer to show that it is safe to rely on that document and it makes nodifference whether the computer document has been produced with or without theinput of information provided by the human mind and thus may or may not behearsay (per Lord Griffiths in R v Shephard at p 228).The operation of section69, therefore, is not limited to printouts that fall within sections 23 or 24 ofthe 1988 Act. (6)ReliabilityIf there is a dispute as to the admissibility of a computer printout in acriminal case involving a jury, the judge should hold a voir dire. A partyseeking to admit a printout under section 24 (or section 23) must establish thefoundation requirements of both that section and section 69. The judge, indeciding whether the prosecution has established these requirements, shouldapply the criminal standard of proof. (7) Although, as we shall see, theadditional requirements of section 69 can be proved by certificate, thefoundation requirements of section 24 (or section 23) must be proved by evidenceunless the other party makes admissions or allows the statement to be read.
There is also a third common law requirement, before the judge can decide onadmissibility, namely that appropriate authoritative evidence must be adduced todescribe the function and operation of the computer (eg R v Cochrane).
In R v Governor of Pentonville Prison ex p Osman 1989 3 All ER 701 it wasargued that printouts were inadmissible because the prosecution had failed toprove the proper operation of the computers required by section 69. HoweverLloyd J held that “where a lengthy computer output contains no internal evidenceof malfunction…it may be legitimate to infer that the computer which made therecord was functioning correctly” (at p 727).
In R v Shephard the House of Lords held that it will very rarely be necessary tocall an expert to prove that the computer is reliable. The defendant was chargedwith theft from a store. A store detective gave evidence that she had examinedall the till rolls for the relevant day from the tills, which were linked to acentral computer, and that they contained no record of the unique product codefor some goods found in the defendant’s possession. She also said that there hadbeen no trouble with the central computer. On appeal it was argued that theevidence did not satisfy section 69 since oral evidence that the computer wasoperating properly is not admissible unless given by a person qualified to signthe certificate under para 8(d) of Schedule 3 which provides that:”In any proceedings where it is desired to give a statement in evidence inaccordance with section 69 above, a certificate -…. (d) purporting to besigned by a person occupying a responsible position in relation to the operationof the computer, …..shall be evidence of anything stated in it; and for thepurposes of this paragraph it shall be sufficient for a matter to be stated tothe best of the knowledge and the belief of the person stating it.”Dismissing the appeal, it was held that section 69 can be satisfied by the oralevidence of a person familiar with the operation of the computer who can giveevidence of its reliability and need not be a computer expert. Lord Griffithssaid that:”Computers vary immensely in their complexity and in the operations they perform.
The nature of the evidence to discharge the burden of showing that there hasbeen no improper use of the computer and that it was operating properly willinevitably vary from case to case. I suspect that it will very rarely benecessary to call an expert and…in the vast majority of cases it will bepossible to discharge the burden by calling a witness who is familiar with theoperation of the computer in the sense of knowing what the computer is requiredto do and who can say that it is doing it properly.”This approach was adopted in Darby v DPP The Times 4 November 1994. Theappellant had driven her car into an area of road subject to a 30 mph speedlimit. At that point a police speed trap was being operated. A police officerwas operating a device known as a GR Speedman and he concluded that theappellant had exceeded the speed limit by driving at 43 mph. It was submittedthat the evidence of the reading of the GR Speedman was inadmissible if it washeld to constitute a document. It was also contended that the evidence of theread-out required certification and that, whilst oral evidence of certificationwould be admissible, the police officer could not give such evidence as he wasnot an expert in the workings of the machine, only its operation.
Potts J adopted the approach of Lloyd LJ in the Shephard case and assumed thatthe machine was a computer and that the visual image was a document produced bya computer. He also referred to the principle enunciated in Lord Griffiths’speech above and accordingly found no problem in holding that, on the basis ofthe evidence of the police officer, who was a trained and experienced operatorof the device, the machine was working correctly. The appeal was consequentlydismissed.
Thus it seems that the provisions in section 69 are capable of being appliedwithout undue difficulty. However, it is interesting to note that Rose LJpointed out that if the GR Speedman had been central to this case and if it hadproduced a printout on which the prosecution had relied then it may well havebeen caught by section 10(1)(c) (8) of the Civil Evidence Act 1968 (section118(1) of PACE 1984 provides that a ‘document’ within that Act has the samemeaning as in Part I of the CEA 1968). This would have meant that as a documentwithin the meaning of section 10(1)(c) it would have constituted a documentrequiring certification within the meaning of section 69 and the terms of para 8of Sch 3. But it was the police officer’s opinion evidence which was central tothe case and that was capable of being corroborated by a technical device, theaccuracy of which had been established. Thus it appears that the conditions foradmissibility for computer output in a criminal case are less demanding if theevidence provided by the machine is merely corroborative.
The ambiguities and illogicality arising from the complex conditions foradmissibility of computer evidence can clearly be seen in the recent case ofMcKeown v DPP 1995 Crim LR 69 where the Divisional Court held that if itcannot be proved that the computer was operating properly the computer evidencewill be inadmissible. This flies in the face of Lloyd LJ’s dictum in the Osmancase since the conclusion was reached despite the fact that evidence showed thatthe malfunction did not affect the accuracy of the information. The caseconcerned an appeal by Miss McKeown against her conviction for driving afterhaving consumed so much alcohol that she was over the legal limit contrary to s5(i)(a) of the Road Traffic Act 1988 and Sch 2 of the Road Traffic Offenders Act1988.
The appellant underwent a breath test using the Lion Intoximeter 3000 breathtesting device. This machine has a visual display and a memory which stores anumber of results. Four printouts were produced by the machine and these werecertified by the officer in charge in accordance with s 69 PACE. On hisstatement the officer recorded the time shown on his watch as the machine wasthirteen minutes out. The submission of the appellant was that the visualdisplays and printouts were inadmissible on the basis that since the timingdevice was thirteen minutes slow it could not be shown according to s 69(1)(b)’that at all material times the computer was operating properly, or if not, thatany respect in which it was not operating properly or was out of operation wasnot such as to affect the production of the document or the accuracy of its’contents’. On behalf of the respondent it was argued that the words ‘to amaterial degree’ should be read into the statutory provision and that theincorrect timing did not in itself render the evidence from the machine de factoinadmissible.
Dr Williams, a director of the laboratories who supplied the breath testingmachine, had been called as an expert witness on behalf of the prosecution. Itwas held that although he was not an electronics expert his qualifications andexperience entitled him to give evidence in respect of the machine. The courtaccepted his evidence that the working and accuracy of the breathalyser was notaffected in anyway by the clock. However, despite these findings the court tookthe view that there was substance in the appellant’s submission that on thewording of s 69(1)(b) the inaccurate timing mechanism on the machine renderedthe print outs produced by it inadmissible. The appeal was allowed andconviction quashed wholly on the basis that, despite the evidence, theprosecution could not prove that the machine was working properly. The outcome,although in line with the statutory requirements of section 69(1) (b), is quiteabsurd since there was no question as to the reliability of the evidence.
The McKeown case also gives rise for concern in that the defence raised thesmoke-screen of concentrating on the fallibility of the computer evidence ratherthan the reliability of such evidence. This point was raised by Dr Castell whenhe delivered The VERDICT Report to the Treasury in 1987. (9) He was perturbedthat the current law could be effectively exploited by defence counsel toundermine a prosecution. The Law Commission in its Consultation Paper (Law ComCP No 138) claim that there is support for this contention in that judgescommented on the lengthy cross-examination of prosecutions’ computer experts. Itwill be recalled that the standard of proof in a criminal case for evidencetendered by the prosecution is ‘beyond all reasonable doubt’. The intricacy andcomplexity of many modern computer systems may make it relatively easy toestablish a reasonable doubt in the juror’s mind as to proper functioning of thecomputer. Using the example of the McKeown case it appears that in the absenceof a presumption that the computer is working means that it may be quite easy toraise such a smoke screen. It would seem perfectly feasible that where there aredoubts as to the reliability of computer generated evidence these doubts shouldnot go to the issue of admissibility but rather to the weight of the evidence.
As we have seen in Shephard s 69 only applies where computer generated documentsare tendered in evidence and there is an affirmative duty on those introducingcomputer evidence to show that at all times it is safe to rely on it. Thus whenapplying a literal interpretation of the statutory provision illogicality andconfusion reigns as demonstrated by the McKeown case. Furthermore it has beenheld that s 69 does not apply where a witness uses computer generated evidenceto refresh his or memory nor where it is used by an expert to reach a conclusion.
In Sophocleous v Ringer 1988 RTR 52, another driving with excess alcohol case,evidence was given against the accused by an analyst who had used a computerwhich produced a graph illustrating the levels of alcohol in the blood stream.
The graph was not put in evidence but the analyst was allowed to look at it torefresh her memory. As the graph had not been put in evidence the court heldthat s 69 did not apply.
The same outcome is illustrated in a recent Court of Appeal case, R v Golizadeh1995 Crim LR 232. In this case a brown substance was found in the possessionof the appellant which turned out to be a Class A drug (opium). The susbstancewas analysed through a machine which produces a print out in the form of apattern; this pattern is then interpreted by an expert to determine the chemicalconstituents of the substance. In arriving at his conclusion that the substancewas indeed opium the expert witness relied on his own interpretation of theprint out and the opinion of another expert called to give evidence.
One ground of appeal was that under s 69 PACE the evidence should have beenexcluded on the basis that it was based on the computer print outs and wastherefore inadmissible. The Court of Appeal rejected this argument and held thats 69 did not apply. Morland J reiterated Lord Griffith’s speech in the Shephardcase whereby he stated that the object of s 69 “requires anyone who wishes tointroduce computer evidence to produce evidence that will establish that it issafe to rely on the documents produced by the computer”. Thus it is clearly thecase that s 69 will only apply where computer print outs are actually put inevidence. Since in the present case the print outs had merely been used by theexperts in reaching their findings as to the chemical constituents of thesubstance s 69 had no application on the facts of the case. In the words of theLaw Commission in its recent Consultation Paper “if it is safe to admit evidencewhich relies on and incorporates the output from the computer, it is hard to seewhy that output should not itself be admissible” (Law Com CP No 138, para 14.13).
The irony of the situation is that it appears perfectly acceptable for evidenceto be adduced which is based on computer generated print outs but at the sametime if the computer evidence itself was to be presented to the court then thehurdle of complying with s 69 would have to be surmounted.
Are the special provisions necessary?As we have seen, the statutory provisions impose special conditions on theadmissibility of computer output. Are these justified? What is it that isspecial about computer-generated documents and that distinguishes them fromtheir paper equivalents? It is obvious from examination of the admissibilityrequirements that computer evidence is regarded as suspicious in severalrespects The main problem is concerned with the authentication and accuracy ofcomputer records. It is almost as if the technology is believed to be inherentlyinaccurate. (10) Section 69 PACE requires some minimum proof of accuracy beforethe document is admissible. The court must be satisfied of the reliability ofthe statement as a true record of what the witness observed and also of itsauthenticity as an accurate record of what was intended to be recorded. As aresult it is necessary to show that at all material times the computer had beenfunctioning properly, or at least that any malfunction had not affected theaccuracy of the information.
It was envisaged by the Criminal Law Revision Committee (CLRC 1972, para 259)that there would be many cases where the document might have become corrupted bysoftware errors or hardware malfunctions. It is the contention of this articlethat this suspicion was probably unfounded on the basis that there has been hasbeen no tangible evidence to date illustrating why computer records are likelyto be less accurate than those contained on paper. Paper based records are alsosusceptible to alteration and deterioration yet, where it is alleged that suchalteration has taken place, the paper document remains admissible and thechallenge goes to the question of its weight as evidence, to be decided on thebasis of the evidence called to prove falsification or authentication.
Regarding documentary evidence para 3 of Schedule 2 to the Criminal Justice Act1988 provides that:”In estimating the weight, if any, to be attached to … a statement given inevidence under section 23 or section 24 regard shall be had to all thecircumstances from which any inference can reasonably be drawn as to itsaccuracy or otherwise”.
Although no particular circumstances are specified, it seems safe to assume thatregard may be had, for example, to the following matters: whether the person whomade the statement in a document did so contemporaneously with the occurrence orexistence of the facts dealt with in the statement; whether any person whosupplied the information did so contemporaneously with the occurrence orexistence of the facts dealt with in that information; and whether or not suchpersons or the ‘creator’ of the document containing the information had anyincentive to conceal or misrepresent the facts.
In stark contrast to this, unless it can be shown that there is no chance ofunauthorised use of a computer system, or of system failure, the same documentstored on computer is inadmissible under the additional requirements of section69 PACE (eg McKeown v DPP).
Doubts concerning the accuracy of information recorded on computers applyequally to paper-based systems, as do those concerning authentication. As withpaper records, the necessary degree of authentication can be proved through oraland circumstantial evidence, if available, or via technological features of thesystem or record. (11) Although a paper document can be authenticated by itsauthor appending a signature, various technical ways of authenticating c
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