Proliferation of e-Evidence: Reliability Standards and the Right to a Fair Trial

Abstract By early 2024, 85% of criminal investigations involved digital data in the European Union (EU or the Union). Despite the progressive development of the EU’s toolbox in the field of judicial cooperation in criminal matters, there is little emphasis on establishing European minimum standards for the reliability of digital evidence. Furthermore, the Court of Justice of the EU ( cjeu ) has reiterated that, as EU law currently stands, it is for the domestic law to determine the rules relating to the admissibility and assessment of evidence obtained and to implement rules governing the assessment and weighting of such material. In this regard, most legal systems assume that evidence is authentic unless proven otherwise. Nonetheless, a mechanism governing this area is particularly important, as digital evidence introduces additional concerns, such as potential technological biases and the increasing prevalence of manipulated content, like deepfakes, compared to traditional evidence. Furthermore, the lack of reliability assessments at time of the proceedings significantly impacts on the fairness of the criminal proceedings in respect to the right to equality of arms. In this regard, the Union legislator, through Recital 59 of Regulation 2024/1689, which establishes harmonised rules on artificial intelligence ( ai Act), acknowledges the vulnerabilities linked to the deployment of ai systems by law enforcement authorities. These systems can create a significant power imbalance, potentially leading to surveillance, arrest, or deprivation of a person’s liberty, along with other adverse impacts on fundamental rights guaranteed by the Charter of Fundamental Rights of the EU (Charter). Consequently, certain ai systems used by the police are classified as high-risk due to their impact on ‘the exercise of important procedural fundamental rights, such as the right to an effective remedy and to a fair trial as well as the right of defence and the presumption of innocence, could be hampered, in particular, where such ai systems are not sufficiently transparent, explainable and documented’. Furthermore, the Union recognises the importance of accuracy, reliability, and transparency in these ai systems to prevent adverse impacts, maintain public trust, and ensure accountability and effective redress. However, it is unclear how the ai Act will contribute to the establishment of reliability standards in cases where digital evidence is gathered or generated by ai systems. In addition to that, the Union has the competence to set minimum standards for the mutual admissibility of evidence between Member States, in accordance with Article 82(2) of Treaty of the Functioning of the European Union ( tfeu ). However, for the time being, it appears reluctant to shed light on the matter despite its implications on the fairness of the criminal proceedings. Although the new Regulation 2023/1543 on e-Evidence (e-Evidence Regulation) acknowledges the challenges faced by law enforcement and judicial authorities in exchanging electronic evidence, it fails to address this specific aspect. The paper seeks to determine whether these laws, as they stand, can safeguard the requirements for reliability standards in connection with the right to a fair trial, or/and if there is a clear need for a legislative proposal. To this end, after providing some insights about the Area of Freedom, Security and Justice ( afsj ) (Section ii ), the paper will address the concepts of digital evidence and reliability and their relevance in relation to the right of fair trial (Section iii ). Furthermore, it will provide an analysis of the relevant provisions within the e-Evidence Regulation (Section iv ).