What is error in any given case depends, of course, not only on the evidence, but also on the nature of the findings or conclusions made by the primary judge. The demonstration of error may not be straight-forward where findings or conclusions involve elements of fact, degree, opinion or judgment ...
This is not to elevate ordinary factual findings to the protected position of those based on credit, but it is to make clear, first, the advantages of the trial judge and, secondly, the need for demonstration of error. The inability to identify error may arise in part from the unwillingness of the appeal court to be persuaded that it is in as good a position as the trial judge to deal with the issues, because of the kinds of considerations referred to in [24] above. Or, it may be that the nature of the issue is one such that (though not a discretion) there cannot be said to be truly one correct answer. In such cases the availability of a different view, indeed even perhaps the preference of the appeal court for a different view, may not be alone sufficient: see Zuvela v Cosmarnan Concrete Pty Ltd [1996] HCA 30; (1996) 71 ALJR 29 at 30-31; [1996] HCA 30; 140 ALR 227 at 229-230. In circumstances where, by the nature of the fact or conclusion, only one view is (at least legally) possible (for example, the proper construction of a statute or a clause in a document, where, although, as often said, minds might differ about such matters of construction, there can be but one correct meaning: see generally Enfield City Corporation v Development Assessment Commission [2000] HCA 5; (2000) 199 CLR 135, 151-156) the preference of the appeal court for one view would carry with it the conclusion of error. However, other findings and conclusions may be far more easily open to legitimate differences of opinion eg valuation questions, see Fenton Nominees Pty Ltd v Valuer-General (1981) 27 SASR 258, 259-263; 47 LGRA 71 at 73-76.
...
... in that process of considering the facts for itself and giving weight to the views of, and advantages held by, the trial judge, if a choice arises between conclusions equally open and finely balanced and where there is, or can be, no preponderance of view, the conclusion of error is not necessarily arrived at merely because of a preference of view of the appeal court for some fact or facts contrary to the view reached by the trial judge.
The degree of tolerance for any such divergence in any particular case will often be a product of the perceived advantage enjoyed by the trial judge. Sometimes, where matters of impression and judgment are concerned, giving 'full weight' or 'particular weight' to the views of the trial judge might be seen to shade into a degree of tolerance of divergence of views ... However, as Hill J said in Commissioner of Taxation (Cth) v Chubb Australia Ltd [1995] FCA 1146; (1995) 56 FCR 557, 573, 'giving full weight' to the view appealed from should not be taken too far. The appeal court must come to the view that the trial judge was wrong in order to interfere. Even if the question is one of impression or judgment, a sufficiently clear difference of opinion may necessitate that conclusion.