The concept of obviousness of risk and the breach of duty
36 CBH's submissions require due regard to be had to the more recent statements by the High Court on the subject of obviousness of risk. The latest discussion occurs in Vairy v Wyong Shire Council [2005] HCA 62 and Mulligan v Coffs Harbour City Council [2005] HCA 63 but the High Court did not speak with one voice in these cases and it is helpful to commence the inquiry by referring to a joint judgment of five members of the High Court (Gummow & Callinan JJ did not sit) delivered six months before Vairy and Mulligan, namely Thompson v Woolworths (Queensland) Pty Ltd (2005) 79 ALJR 904.
37 In Thompson the High Court (Gleeson CJ, McHugh, Kirby, Hayne and Heydon JJ) said at [36], 911:
"The obviousness of a risk, and the remoteness of the likelihood that other people will fail to observe and avoid it, are often factors relevant to a judgment about what reasonableness requires as a response."
38 It is also helpful at this stage to repeat the reminders given by Callinan and Heydon JJ in Mulligan at [76] of the several occasions in which various members of the High Court in recent times have affirmed the relevance and importance of the concept of obviousness of risk. For example, as their Honours remarked, in Swain v Waverley Municipal Council (2005) 79 ALJR 565 at 593 Gummow J said that the obviousness of the risk was important "at least in the mix of factors to be taken into account" and in Woods v Multi-Sport Holdings Pty Ltd (2002) 208 CLR 460, "Gleeson CJ, with whom Hayne J agreed, thought obviousness decisive in relation to the recreational activity in which the appellant was there engaged". Callinan and Heydon JJ remarked that what Callinan J had said in Woods also emphasised the importance of obviousness and they noted, (at [77]), that in Ghantous v Hawkesbury City Council (2001) 206 CLR 512, "five judges of this Court stressed, and treated obviousness as a decisive factor" (at [8] 526, per Gleeson CJ, [163] 581, per Gaudron, McHugh and Gummow JJ, [355] 639, per Callinan J).
39 For the reasons that follow, I do not think, with respect, that anything said by the majority of the justices in Vairy and Mulligan departs in substance from what was said in Thompson and what had earlier been said on this topic in the instances mentioned by Callinan and Heydon JJ.
40 There were differences in the High Court as to the correctness of the principles applied by the Court of Appeal in Wyong Shire Council v Vairy; Mulligan v Coffs Harbour City Council [2004] NSWCA 247 - and indeed as to what principles the Court of Appeal applied. I am required, in order to reveal fully my reasoning (based on the judgments of the High Court in Vairy and Mulligan) as to the correct approach to be adopted to the concept of obvious risks, to set out my understanding of the basis of the Court of Appeal's decision. This is necessary as a majority in number of the justices of the High Court approved of the way in which the Court of Appeal dealt with this issue.
41 I think it sufficient to state that Tobias JA, who gave the leading judgment of the Court of Appeal, placed considerable reliance on the fact that the plaintiffs in those cases knew that the water into which they dived was of unknown depth and the danger of diving into it was obvious. His Honour found that, in the particular circumstances of those cases, because of the obvious danger it was not unreasonable for the defendants to fail to warn of the foreseeable risk of diving. I do not understand the Court of Appeal to have proceeded on the basis that diving cases constituted a separate category of negligence, or that obviousness of the risk meant more in diving cases than in other cases, or that the sole fact that the risk was obvious meant that the plaintiffs should fail. On my understanding of the judgment of Tobias JA, his Honour regarded the obviousness of the risk, in the particular circumstances of the two cases, to be so important a factor that the defendant authorities did not act unreasonably in not giving a warning of the risks that were present. Beazley JA, who dissented in Vairy, did not disagree as to the principles that applied but had a different view after weighing up all the facts.
42 In Mulligan, the High Court unanimously (but for reasons that differed) dismissed the appeal from the decision of the Court of Appeal. In Vairy the appeal was dismissed by a majority (again for reasons that differed) consisting of Gummow, Hayne, Callinan and Heydon JJ; Gleeson CJ and Kirby J (who delivered a joint judgment) and McHugh J dissented.
43 In Mulligan Gleeson CJ and Kirby J, in a joint judgment, said at [7] that, having considered the reasons of the Court of Appeal (and of the primary judge), they found no error. In Vairy their Honours said at [7]:
"The obviousness of a danger can be important in deciding whether a warning is required."