What is a fair criminal trial?

The concept of trial fairness is central to academic research in criminal procedure and, unlike other concepts that seem to preoccupy exclusively the scholar, it is of great significance in legal practice. And yet, trial fairness is undertheorised, both in the academic literature and in the case law. The paper advances a theory of fairness for the criminal trial; moreover, a theory that is ‘relatively freestanding’, in that its success does not require committing to a specific account of the values that ought to inform the trial. According to this theory, trial fairness is about participation, and it requires that all those who have a justified interest concerning the outcome of the trial are given opportunities to participate in it that are proportional to the weight of their justified interest. The paper analyses the points of contact and of divergence between the advanced conception of trial fairness and those sketched in the literature and case law.