question (b): mistake of fact
55 The defence of honest and reasonable mistake of fact goes back at least to 1889: see R v Tolson (1889) 23 QBD 168. It has been considered by the High Court of Australia in (inter alia) Proudman v Dayman [1941] HCA 28; 67 CLR 536 and He Kaw Teh v The Queen (1985) 157 CLR 523.
56 It is unnecessary to go in detail to those cases. The defence has more recently been considered by this Court in the context of an appeal in relation to a prosecution under the Clean Waters Act 1990 in SRA (NSW) v Hunter Water Board (1992) 28 NSWLR 721. Reiterating what had been said by Dixon J (as he then was) in Proudman v Dayman, Gleeson CJ outlined the defence as:
" ... that the defendant had reasonable grounds for believing in the existence of a state of facts, which, if true, would take his act outside the operation of the enactment, and that on those grounds he did so believe."
57 The onus lies upon the prosecution to negative the defence, once raised and to do so beyond reasonable doubt: SRA, p 726.
58 Mistake, even if honest and reasonable, as to a matter of law will not establish the defence or otherwise exonerate a person from the criminal consequences of conduct that otherwise would give rise to criminal liability.
59 It is not easy to determine the path which led Talbot J to his finding that, by reason of honest and reasonable mistake of fact, GWS was not guilty of the offence (in so putting the issue, I do not overlook the onus of proof). One thing which is not clear is the "fact" or "facts" as to which GWS claimed to have been mistaken. It is convenient to go to his Honour's reasons for judgment in this respect. At [104] he identified seven "mistakes of fact" upon which, he said, GWS relied. These included:
"(1) That the existing and operating first flush system was the subject of a licence application considered and approved by the EPA.
(2) If GWS catches the first 10mm of rain at Goulburn via a pipe and contour banks then GWS can divert the rest off site and if GWS catches the first 23mm of rain at Yarra via a pipe and contour banks then GWS can divert the rest off site.
(3) If GWS's systems operate as designed and installed then it can discharge in accordance with the design operating perameters."
60 I do not propose to restate all of the seven purported "facts". In the stated case, these seven "facts" were restated, but in the following context:
"[GWS] contended on the basis that its primary defence was not established - ..."
[his Honour then set out the seven "facts"]
61 It does not appear, in the way the stated case is framed, that those "facts" were put forward as being matters as to which GWS was mistaken. Rather, as the stated case reads, these seven matters were put as matters of actual fact, not as facts GWS mistakenly believed to be true. However, returning to the reasons for judgment, his Honour went on to say:
"113 The belief claimed to be held by GWS was that the EPL was not breached because the licence authorised the continued operation of a system which was already in place and functioned as a first flush system thereby incorporating the potential for the discharge of stormwater runoff off site. If, contrary to the court's finding, the licence did not allow for a discharge off the site then that is a matter to be determined by a proper construction of the licence. [GWS] must show that its interpretation of the effect of the licence is a conclusion of fact that has the consequence of [GWS] making a mistake in relation to the regulation of the site and thereby creating a belief or assumption that the acts in question were lawful under the PEO Act.
114 In Collector of Customs v Agfa-Gevaert Ltd (1995 - 1996) 186 CLR 359 at 395 [[1996] HCA 36] the High Court appears to have embraced the proposition that when words are used according to their ordinary meaning and it is reasonably open to hold that the facts of the case fall within those words the question as to whether they do or do not is one of fact . The mistake of [GWS], if there was one, amounted to a misunderstanding of the effect of condition A4.1 and O3.5 of the EPL. The issue relates only to the ordinary meaning of the words. The High Court in Agfa-Gevaert raised a serious doubt that the effect or construction of a term whose meaning and interpretation is established is a question of law." (emphasis added)
62 At para 55 of the stated case, his Honour said:
" I found that the mistake of [GWS], if there was one, amounted to a misunderstanding of the effect of conditions A4.1 and possibly O3.5 of the amended EPL . On the basis that its primary defence was not established, I was of the opinion that [GWS] would have held a mistaken belief as to the fact of how the licence operated including conditions A4.1 and possibly O3.5 of the EPL." (emphasis added)
63 In coming to the conclusion he did, his Honour relied upon evidence given by Mr Kneebone, and it appears to have been Mr Kneebone's evidence that provided the foundation for the seven "facts" set out in [104] of the reasons for judgment.
64 Since Talbot J made his findings and gave his reasons, the High Court of Australia has delivered judgment in Ostrowski v Palmer [2004] HCA 30; 206 ALR 442. There, the respondent held a fishing licence under Western Australian fisheries legislation. Acting on incorrect information given to him by a WA fisheries officer, he fished in an area in which he was not, in law, entitled to fish. On the basis of the information given to him, he held an honest but mistaken belief that the licence authorised him to fish in that area. The High Court unanimously held that his mistake was a mistake of law and therefore did not afford him the defence that is the Western Australian statutory equivalent of the defence here under consideration. At [12] Gleeson CJ and Kirby J held that the only mistake that the respondent had made was a mistake that resulted from his ignorance of the law; at [48] McHugh J held that the mistake was one of law, not fact. The joint judgment of Callinan and Heydon JJ is to the same effect.
65 In my opinion the present case is indistinguishable. The series of facts set out at para 50 of the stated case and [104] of the judgment, are not facts, which, if true, would have taken GWS's act outside the operation of s120 of the PEO Act. The relevant mistaken belief only hypothesised and not expressly found by Talbot J, was as to "how the licence operated". That, as in Ostrowski, was (or would have been) a mistake of law. It follows that the question (b) should also be answered "yes".
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