ERWIN v IVECO TRUCKS AUSTRALIA LTD  NSWCA 113
Basten JA at 1; Campbell JA at 5; Sackville AJA at 12
86 An important element in the primary Judge’s reasoning in the present case was the finding that the manufacture in 1989 of the steering mechanism in the Truck conformed to the industry norm at that time. Subject to legislation, the general principle remains that stated by Latham CJ in Mercer v Commissioner for Road transport and Tramways (NSW)  HCA 71; 56 CLR 580, at 589:
“The mere fact that a defendant follows common practice does not necessarily show that he is not negligent, though the general practice of prudent men is an important evidentiary fact. A common practice may be shown by evidence to be itself negligent.”
87 It follows that evidence of adherence to common practice in an industry, although important, is not necessarily determinative of whether a breach of duty has occurred: Council of the Shire of Muswellbrook v Lettice  NSWCA 359, at -, per Meagher JA (with whom Stein and Heydon JJA agreed); Lanza v Codemo  NSWSC 72, at , per Wood CJ at CL; Rogers v Whitaker  HCA 58; 175 CLR 479, at 487, per Mason CJ, Brennan, Dawson, Toohey and McHugh JJ; Rosenberg v Percival  HCA 18; 205 CLR 434 (cf CL Act, s 5O, dealing with the standard of care owed by a person practising as a professional).
88 It is, however, important to bear in mind the observations of McHugh J (with whom Gummow and Heydon JJ agreed on this point) in Dovuro Pty Ltd v Wilkins  HCA 51; 215 CLR 317. In that case the question was whether a supplier of imported canola seeds had breached its duty of care to a Western Australian farmer by not disclosing the presence of weed seeds in the canola. There was no evidence that at the time the seeds were supplied the particular weeds were regarded as presenting a danger to Western Australian agriculture.
89 McHugh J said (at 329 ):“If negligence law is to serve any useful social purpose, it must ordinarily reflect the foresight, reactions and conduct of ordinary members of the community or, in cases of expertise, of the experts in that particular community. To hold defendants to standards of conduct that do not reflect the common experience of the relevant community can only bring the law of negligence, and with it the administration of justice, into disrepute. That is not to say that a defendant will always escape liability by proving that his or her conduct was in accord with common practice. From time to time cases will arise where, despite the common practice in a field of endeavour, a reasonable person in the defendant’s position would have foreseen and taken steps to eliminate or reduce the risk that caused harm to the plaintiff. But before holding a defendant negligent even though that person has complied with common practice, the tribunal of fact had better first make certain that it has not used hindsight to find negligence. Compliance with common practice is powerful, but not decisive, evidence that the defendant did not act negligently. And the evidentiary presumption that arises from complying with common practice should be displaced only where there is a persuasive reason for concluding that the common practice of the field of activity fell short of what reasonable care required.”
See also McDonald v Girkaid Pty Ltd  NSWCA 297, at , per McColl JA (with whom Beazley JA and Young CJ in Eq agreed).