This article discusses whether a rule that requires the defence to give prior notice of its strategy and arguments to the prosecution has any bearing on the role of the prosecutor being inquisitorial or adversarial. The rule of special defences in Scottish criminal procedure, which combines inquisitorial and adversarial characteristics, is analysed. On the basis of the historical background of this rule and of Scottish criminal procedure in general, it is submitted that the rule exemplifies inquisitorial ideology, while Scottish procedure is by and large adversarial. The prosecutor may well be expected to use the information gained from an advance notice in an impartial manner, requiring him to investigate exculpatory evidence for the defence. Even though no clear legal duty to that effect exists, the Scottish prosecutor has considerable discretion to engage in informal cooperation with the defence. It is argued that a duty to act impartially may exist within this context of informal cooperation. The Scottish example shows that a rule on special defences need not imply an inquisitorial role for the prosecutor, but it can do so. As prosecutorial discretion and informal cooperation are pivotal for this inquisitorial role, the coherence of the criminal process may change if this discretion is limited by prosecution directives. The resulting loss of the magisterial role of the prosecutor may have to be compensated by a stronger position for the defence, as it may be dependent on the prosecutor’s impartiality for a fair trial.