Most mitigating factors will be relevant only at sentence – for example, good character, remorse, a plea of guilty, stress or personal crisis, or assistance to law enforcement authorities. Some factors, however, are more substantial and may be relevant for both the determination of guilt and for sentence because they relate to the offender’s responsibility or culpability for the offence. Thus a factor such as self-defence may result in a complete acquittal or a conviction for a lesser offence such as manslaughter on a charge of murder, or it may be a mitigating factor at sentencing. Mental disorder is another factor with multiple applications. Youth is generally recognized as a mitigating factor, but is also formally recognized in almost every jurisdiction by a separate sentencing regime that applies different sentencing principles and sanctions from those available in the adult courts.

Of the hundreds of sentencing factors, provocation has been among the most controversial, problematic and variable in its treatment by the law. It is a factor that has been dealt with at all stages of the criminal process and with various consequences. In some jurisdictions it is treated as a partial defence to the crime of murder, reducing it to manslaughter; in others it is now relevant only to sentencing in murder cases. For some non-fatal offences against the person, provocation is a complete defence (resulting in acquittal) in some jurisdictions, while in others it is a mitigating factor to be considered in sentencing.