An appeal court has the power under section 309(3) of the Criminal Procedure Act to increase a sentence of its own motion, even where the appellant has only appealed against conviction and the State has not cross-appealed, provided the appellant is given proper notice that the court is considering increasing the sentence. When such notice is given and the appellant has an opportunity to make submissions, the question of sentence becomes part of the subject matter of the appeal. However, courts must guard against injustice by conducting a proper consideration of whether a prescribed minimum sentence is proportionate to the crime, the criminal, and the legitimate needs of society. Where a court is satisfied that a prescribed sentence would be unjust or disproportionate after considering all the circumstances, it is entitled to characterize those circumstances as substantial and compelling and impose a lesser sentence. An injustice need not be "shocking" to justify departure from a prescribed sentence. Where a sentencing court has not misdirected itself and has properly exercised its discretion, an appeal court should not interfere with the sentence imposed.