176 This appeal is by way of rehearing, and the Court must “conduct a real review of the trial and, in cases where the trial was conducted before a judge sitting alone, of that judge’s reasons”: Fox v Percy at ; see also Anikin v Sierra  HCA 64; (2004) 79 ALJR 452 at ; Lujans v Yarrabee Coal Company Pty Ltd  HCA 51; (2008) 249 ALR 663 at , -.
177 The appeal is not a completely fresh hearing, and there are necessarily “the ‘natural limitations’ that exist in the case of any appellate court proceeding wholly or substantially on the record” (Fox v Percy at ). So in Swain v Waverley Municipal Council  HCA 4; (2005) 220 CLR 517 at  Gleeson CJ said -
“In the common law system of civil justice, the issues between the parties are determined by the trial process. The system does not regard the trial as merely the first round in a contest destined to work its way through the judicial hierarchy until the litigants have exhausted either their resources or their possibilities of further appeal. Most decisions of trial courts are never the subject of appeal. When there is an appeal, the appellate court does not simply re-try the case. Depending on the nature of the appeal provided by statute, courts of appeal act according to established principles by which their functions are constrained. Those principles reflect the primacy of the trial process and the practical limitations upon the capacity of a court which does not itself hear the evidence justly to disturb an outcome at first instance.”
178 Those limitations include the trial judge’s advantage concerning factual findings affected by demeanour, but are not limited to that advantage; conversely, as explained by Allsop P in Yarrabee Coal Company Pty Ltd v Lujans  NSWCA 85 at , an appellate court has some advantages over the trial judge, in evaluation of the evidence with counsel’s assistance and discussion and debate with counsel and between the members of the Court and the “capacity for appellate synthesis and perspective”.
179 In Fox v Percy Gleeson CJ and Gummow and Kirby JJ said at  that -
“ … the mere fact that a trial judge necessarily reached a conclusion favouring the witnesses of one party over those of another does not, and cannot, prevent the performance by a court of appeal of the functions imposed on it by statute. In particular cases incontrovertible facts or uncontested testimony will demonstrate that the trial judge’s conclusions are erroneous, even when they appear to be or are stated to be, based on credibility findings.” (citations omitted)
180 Their Honours went on to say that in some, quite rare, cases where the facts fell short of being incontrovertible, the appellate court could conclude that the trial judge’s decision was glaringly improbable or contrary to compelling inferences, and if it did so should give effect to its own conclusion notwithstanding that the trial judge had expressly or implicitly been influenced by an opinion concerning the credibility of witnesses.
181 The constraints brought by the trial judge’s advantages to the appellate court’s review of fact-finding do not exclude recognition of error in the process of fact-finding in other respects. In Abalos v Australian Postal Commission (1990) 171 CLR 167, one of the trilogy of cases said in Fox v Percy at  to remind of the limits under which appellate judges typically operate when compared with trial judges, McHugh J (with whom Mason CJ and Deane, Dawson and Gaudron JJ agreed) took from the speech of Lord Sumner in SS Hontestroom v SS Sagaporack (1927) AC 37 at 47 that appellate judges are in a position of disadvantage against the trial judge “unless it can be shown that [the trial judge] has failed to use or has palpably misused his advantage”. These words, which have achieved mantra-like status, encompass where the trial judge has made credibility based findings (even expressly by regard to demeanour) for reasons which in whole or in part do not truly go to the reliability or veracity of the relevant evidence, or without taking account of an important consideration or considerations material to evaluation of the credibility or veracity.
30 The primary Judge’s conclusion that the Council breached its duty of care to the respondent involved an evaluation by his Honour of a range of considerations, some of which compete with each other. Nonetheless, the test for determining whether appellate intervention is justified in relation to that conclusion, given that the primary facts are not in dispute, is that laid down in Warren v Coombes  HCA 9; 142 CLR 531, at 551, per Gibbs ACJ, Jacobs and Murphy JJ:
“[T]he established principles are, we think, that in general an appellate court is in as good a position as the trial judge to decide on the proper inference to be drawn from facts which are undisputed or which, having been disputed, are established by the findings of the trial judge. In deciding what is the proper inference to be drawn, the appellate court will give respect and weight to the conclusion of the trial judge, but, once having reached its own conclusion, will not shrink from giving effect to it. These principles, we venture to think, are not only sound in law, but beneficial in their operation.
It is to be remembered that Warren v Coombes itself was a case in which the issue was whether a duty to exercise reasonable care had been breached: see Certain Lloyds Underwriters v Giannopoulos  NSWCA 56, at -, per Campbell JA (with whom Giles and Ipp JJA agreed).
31 I do not think that the appellants have made out their complaint that the primary Judge failed to apply the direction in s 5B(1)(b) of the CL Act that a person is not negligent in failing to take precautions against a risk of harm unless the risk “was not insignificant”. The primary Judge directed his attention to this issue and expressly concluded that the risk was not only foreseeable but was not insignificant. Indeed, he found that the risk was “very obvious and perhaps an accident waiting to happen”.
107 The primary judge was not, with respect, qualified to discount/reject expert evidence because of his own view about the respondent’s over-confidence: Strinic v Singh  NSWCA 15; (2009) 74 NSWLR 419.
80 A trial judge’s assessment of the credit of a witness is protected by the advantage that the judge has in seeing and hearing the witness. There are subtle influences of demeanour to which an appellate court is not privy. The principles that govern such an assessment are well rehearsed: see Abalos v Australian Postal Commission  HCA 47; (1990) 171 CLR 167; State Rail Authority of New South Wales v Earthline Constructions Pty Ltd (In Liq)  HCA 3; (1999) 160 ALR 588; Fox v Percy  HCA 22; (2003) 214 CLR 118; Toll (FGCT) Pty Ltd v Alphapharm Pty Ltd  HCA 52; 219 CLR 165; CSR Ltd v Della Maddalena  HCA 1; (2006) 224 ALR 1. It is a different matter where the assessment of credit is based on wrong factual findings, unless the wrong fact-finding is irrelevant or not so critical as to undermine the advantage that the trial judge otherwise has in assessing the evidence of the witnesses.
81 The issue here is not, directly at least, one of an adverse credit finding based on erroneous findings of fact. Rather, the adverse credit finding was based on a finding that the trial judge made from his own medical knowledge. I have already referred to the principles governing a trial judge’s fact-finding obligations in a court such as the District Court. His Honour’s assumptions and findings in respect of the straight leg test and the conclusion he reached breached that obligation. As the differential result was a critical matter in the assessment of the appellant’s claim, I would consider that his Honour’s reliance on his own medical knowledge to make the adverse credit finding was sufficient to impugn the judgment.