Given the discretionary nature of sentencing, the grounds of manifest excess and manifest inadequacy are difficult to establish. In Karazisis, Ashley, Redlich and Weinberg JJA said:
As with the ground of manifest excess, the ground of manifest inadequacy is a stringent one, difficult to make good. Error of this kind will not be established unless the appellate court is persuaded that the sentence was 'wholly outside the range of sentencing options available' to the sentencing judge. Put another way, it must be shown that it was not reasonably open to the sentencing judge to come to the sentencing conclusion which he/she did if proper weight had been given to all the relevant circumstances of the offending and of the offender.
Sentencing is a discretionary power confided to the sentencing judge and reasonable minds will differ as to what is the appropriate sentence in a particular case. There is no 'correct' sentence. Consideration of current sentencing practices assists in promoting consistency of approach. But sentences in other cases of the same offence are not precedents. Where those sentences can be seen to fall within a range, that range informs, but cannot determine, the appropriate sentence in a particular case.
Fairness demands that there should be reasonable consistency in sentencing. Further, in the absence of such reasonable consistency, the administration of justice is brought into disrepute. It is for the Court to determine what sentences should be considered in order to satisfy the norm of reasonable consistency. In practice, a court is assisted in fulfilling this obligation when the parties bring to the court's attention cases which are said to be comparable to the case in hand. Usually, this is done by the preparation of tables of comparable cases. The utility of such tables will depend on how informative they are. Bare sentencing statistics may suggest a range in respect of sentences for a particular offence. But such statistics will not reveal the circumstances peculiar to a particular case.
Sentencing requires consideration of comparable cases: 'Equal justice requires identity of outcome in cases that are relevantly identical. It requires different outcomes in cases that are different in some relevant respect.' In Pham, the High Court identified the twofold purpose in the use of comparable cases:
(a) they 'provide guidance as to the identification and application of relevant sentencing principles'; and
(b) analysis of them 'may yield discernible sentencing patterns and possibly a range of sentences against which to examine a proposed or impugned sentence'.
In Nguyen v The Queen, Redlich JA (with whom Tate and Whelan JJA agreed) said:
These purposes advance the requirement of reasonable consistency. They advance the underlying value of equality under the law and the search for unifying principles. By the requirement that a discretionary decision must be made in conformity with well settled principles, the law promotes consistency in decision making and diminishes the risk of arbitrary and capricious adjudication.
...
Reasonable consistency is thus achieved by the maintenance of an appropriate relativity between the impugned sentence and similar comparators. Manifest inadequacy or excess is usually demonstrated when an appropriate relativity is absent between the nature of the offending and matters personal to the offender, and sentences imposed in the most closely comparable cases. Thus for example, in Dao v The Queen Nettle JA (as he then was) emphasised that the consistency stated in Wong required that the impugned sentence be in step with 'relevant comparators'.[33]