The Invisible Hand: Expert evidence, epistemic dependence, and judicial discretion in the Turkish Court of Cassation

Abstract

This article analyzes the de facto role of expert reports in Turkish criminal proceedings through the “Invisible Hand” metaphor, examining 20 recent judgments from the Assembly of Criminal Chambers of the Court of Cassation. Although doctrinally classified as non-binding “discretionary evidence,” this study aims to reveal how expert evidence practically shapes judicial “intimate conviction” and the merits of the verdict. Findings from a qualitative case-law analysis demonstrate that the expert report is not merely a technical auxiliary tool but a decisive actor that constructs the factual basis, scrutinizes witness credibility, and steers legal discourse. The study identifies three distinct functions of expert evidence: constitutive , directive , and boundary-setting . Ultimately, it concludes that judicial discretion is significantly narrowed—particularly in complex technical cases and vis-a-vis official expert bodies—creating an “epistemic dependence” that effectively transforms the expert report into the ultimate decision-maker of the trial.