The reputation of ancien régime criminal justice has never recovered from the Calas Affair. The subsequent victory of Voltaire and Beccaria seemed like the triumph of good over evil, the recognition of the rights of the individual in the face of a system which resorted to the most diaphanous of hearsay evidence, an inquisitorial procedure designed to produce a conviction, the threat of perjury charges to dissuade witnesses from changing their minds, torture, and a dreadful execution. It is easy, however, to overdramatise the clash between the ‘enlightened’ principles of our own day and the barbarism of a benighted ancien régime. Both then and now, courts have had the double function of ascertaining the guilt or innocence of an accused, and of helping to maintain law and order in society at large. Both then and now, a balance has had to be established between the protection of the individual suspect and the protection of society as a whole. The operations of the prévôtal court will therefore have to be measured against two standards. In so far as it can be assessed from the transcript of the trials – the same evidence, after all, which was before the court – how fair and reasonable were the decisions of prévôtal magistrates? And in what ways, and how effectively, did prévôtal justice contribute to the defence of law, order and public security?