International review of criminal policy - Nos. 43 and 44/Admissibility of computer generated evidence

D. Admissibility of computer-generated evidence

171. The admissibility of computer-generated evidence is not only important for the use of computer records in the criminal trial process but is also essential to define the extent of the above-described coercive investigatory powers, including those of mutual assistance. In most countries coercive powers are applicable only to material that would be admissible in evidence at a trial, if specific computer data or printouts could not be used as evidence; consequently, they could also not be searched and seized. In practice, the various legal problems are particularly crucial since computer printouts and computer data can easily be manipulated, a phenomenon that is illustratively described as the "second-hand nature" of computer printouts.

172. The admissibility in courts of evidence from computer records depends to a great extent on the underlying fundamental principles of evidence in the particular country. It is necessary to differentiate among varying legal systems, including but not limited to (a) civil law countries and (b) common law countries. Other legal systems, such as Islamic law, incorporate elements from one of these two primary types of systems.

1. Civil law countries

173. Civil law countries and many other countries operate according to the principle of free introduction and free evaluation of evidence (système de l'intime-conviction). In these countries the judge can, in principle, consider all kinds of evidence and then weigh the extent to which the court can rely on the evidence. Legal systems based on these principles do not, in general , hesitate to introduce computer records as evidence. Problems occur only when procedural provisions contain specific regulations for the proof of judicial acts or proof with legal documents.

2. Common law countries

174. Contrary to the legal situation in civil law countries, common law countries are characterized by an oral and adversarial procedure. In these countries a witness can only testify concerning his or her personal knowledge, thereby permitting the statements to the verified by cross-examination. Knowledge from secondary sources, such as other persons, books or records, is regarded as hearsay evidence and is, in principle, inadmissible. Additionally, the "best-evidence" rule generally requires that originals, rather than copies, be introduced as evidence before the court in order to lessen the chance of fraud and error. There are, however, several exceptions to the hearsay and best-evidence rules, such as the "business records exception" or the "photographic copies exception". The business records exception, for example, permits a business record created in the course of everyday commercial activity to be introduced as evidence even if there is no individual who can testify from personal knowledge. If certain prerequisites are met, copies of certain types of records may also be permitted. The questions whether computer files are "real evidence" and whether computer printouts fall under one of the exceptions of the hearsay rule have been the subject of extensive debate. The courts in some common law countries have accepted computer printouts as falling within the business records exception. Other common law countries have elaborated new laws allowing computer records to be admitted as evidence if certain conditions are met.

3. Islamic law countries

175. Under Islamic law, computer crime falls within the area of taazir offences, which operates according to the same principles of evidence law as civilian systems: the free introduction and evaluation of evidence (système de l'intime-conviction). In adjudicating taazir offences the judge weighs the reliability of evidence, and thus computer records are generally admissible in the prosecution of computer crime.