"Secondly, and no less importantly, the reasons of the Court of Criminal Appeal suggest a mathematical approach to sentencing in which there are to be 'increment[s]' to, or decrements from, a predetermined range of sentences. That kind of approach, usually referred to as a 'two-stage approach' to sentencing, not only is apt to give rise to error, it is an approach that departs from principle. It should not be adopted.
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> It departs from principle because it does not take account of the fact that there are many conflicting and contradictory elements which bear upon sentencing an offender. Attributing a particular weight to some factors, while leaving the significance of all other factors substantially unaltered, may be quite wrong. We say 'may be' quite wrong because the task of the sentencer is to take account of all of the relevant factors and to arrive at a single result which takes due account of them all. That is what is meant by saying that the task is to arrive at an 'instinctive synthesis'. This expression is used, not as might be supposed, to cloak the task of the sentencer in some mystery, but to make plain that the sentencer is called on to reach a single sentence which, in the case of an offence like the one now under discussion, balances many different and conflicting features.
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> In R v Thomson[31], Spigelman CJ reviewed the state of the authorities in Australia that deal with the 'two-stage' approach of arriving at a sentence, in which an 'objective' sentence is first determined and then 'adjusted' by some mathematical value given to one or more features of the case, such as a plea of guilty or assistance to authorities. As the reasons in Thomson reveal, the weight of authority in the intermediate appellate courts of this country is clearly against adopting two-stage sentencing and favours the instinctive synthesis approach. In this Court, McHugh and Hayne JJ, in dissenting opinions in AB v The Queen[32] expressed the view that the adoption of a two-stage approach to sentencing was wrong. Kirby J expressed a contrary view. We consider that it is wrong in principle. The nature of the error can be illustrated by the approach adopted by the Court of Criminal Appeal in these matters. Under that approach, the Court takes, for example, the offender's place in the hierarchy and gives that a particular significance in fixing a sentence but gives the sentencer no guidance, whatever, about whether or how that is to have some effect on other elements which either are to be taken into account or may have already been taken into account in fixing the guideline range of sentences. To take another example, to 'discount' a sentence by a nominated amount, on account of a plea of guilty, ignores difficulties of the kind to which Gleeson CJ referred in R v Gallagher[33] when he said that:
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> 'It must often be the case that an offender's conduct in pleading guilty, his expressions of contrition, his willingness to co-operate with the authorities, and the personal risks to which he thereby exposes himself, will form a complex of inter-related considerations, and an attempt to separate out one or more of those considerations will not only be artificial and contrived, but will also be illogical.'
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> So long as a sentencing judge must, or may, take account of all of the circumstances of the offence and the offender, to single out some of those considerations and attribute specific numerical or proportionate value to some features, distorts the already difficult balancing exercise which the judge must perform." (emphasis in original)