Introduction

The manner in which evidence is collected, regulated and assessed has the potential to impact on the fairness of the criminal trial. Most legal systems, irrespective of their exclusionary or ‘inclusionary’ tendencies, provide for rules which prohibit in certain circumstances the use of particular types of evidence, regardless of its probative value. Explaining the nature of the relationship between fairness and improperly obtained evidence and determining when the use of such evidence will undermine the fairness of the proceedings is less than straightforward. These difficulties are reflected in the reluctance of the international bodies responsible for regulating the fairness of criminal proceedings expressly to develop principles to regulate the use of evidence. That is not to say that the potential for matters involving criminal evidence to impact on the fairness of the trial has been completely ignored, only that in many respects these international bodies have been slow to explain the connection between improperly obtained evidence and fairness and that this has necessarily had an impact on the nature of the regulation.

The relationship between the treatment of criminal evidence and the fairness of criminal proceedings is expressly recognised in provisions such as Article 6(3)(d) of the ECHR and in the ECtHR's case law on the privilege against self-incrimination, which has been interpreted as lying at the heart of Article 6(1) of the ECHR. The ECtHR nevertheless seems ill at ease in its role as a regulator of evidential matters. It is not uncommon to read statements in its case law to the effect that, ‘[w]hile Article 6 of the Convention guarantees the right to a fair trial, it does not lay down any rules on the admissibility of evidence as such, which is therefore primarily a matter for regulation under national law’; or that ‘it is not the role of the ECtHR to determine, as a matter of principle, whether particular types of evidence – for example, unlawfully obtained evidence – may be admissible, or indeed, whether the applicant was guilty or not’. Such statements are often cited in the literature on the subject as substantiating the claim that the ECtHR has little to say about the regulation of criminal evidence.