State of New South Wales v Buckland & Ors; Katena Pty Ltd & Ors v Buckland & Ors

The case below: 161 It is convenient to consider, in the first place, the case brought against Katena and Messrs Schafferius and Sawley and his Honour's decision in relation thereto. The case against the State of New South Wales involved different evidence and considerations and it is convenient to consider it later. 162 His Honour indicated, correctly, that the case against Katena and Messrs Schafferius and Sawley depended upon inference rather than direct evidence. After dismissing a claim based on contract, which has not been the subject of appeal, his Honour stated the issues for determination as follows: "The real issues in this case and the ones which the plaintiffs bear the onus to prove are whether the infestation of the 650 paddock by parthenium weed was the result of the stripping of that paddock by one or more of the first defendant's headers on 3 December 1992 and, if so, whether such infestation could be attributed to the negligence of Peter Schafferius or those under his supervision." 163 There were two headers involved in the stripping of the crop. The first was driven by Craig Griffiths, the second by Bart Simpkins, both men being employees of Katena. His Honour found that the infestation occurred as a result of seeds being distributed from the second header, the one driven by Simpkins, during the harvesting of the oats. No seed was distributed by the first header. The first header had commenced the stripping operation and was engaged in it for half an hour to one hour before the second header joined in. For a portion of the time in which the first header was operating, George Buckland was seated beside the driver, Craig Griffiths. His Honour accepted that the reason for his presence was to enable him to direct Griffiths as to the portion of the oat crop which was to be harvested. The rest of the crop was not worth harvesting because of its poor and sparse nature. Mr Buckland's evidence was in conflict with that of Griffiths. Mr Buckland gave detailed evidence as to the course taken by each of the headers. He illustrated this evidence with a coloured sketch plan which became Exhibit D. He testified that the first header entered the crop and, at his direction, was driven round the boundary of the whole portion to be stripped. The boundary so established was for the guidance of each of the headers. More than one round of the whole area was travelled for this purpose, as appears from Exhibit D and from his oral evidence. 164 When the total area of approximately 60 hectares had been thus defined, Mr George Buckland, according to his evidence, then directed that the header be driven across the area in a roughly east west direction, thereby dividing it into a small area of approximately 8 acres to the south and a much larger area, being the balance of the crop to be harvested, to the north. The first header then proceeded to continue the stripping of this northern area, which it did by proceeding in parallel lines moving from the outer edges of the crop towards the centre. After it had made "a few rounds" Mr Buckland left the header, which continued with the stripping operation of the northern portion. 165 Thereafter, as depicted in Exhibit D, the southern area was stripped by the second header which, having completed that task, then joined the first header in the northern portion and, in combination with it, completed the stripping. 166 Exhibit D, through the use of pink colour to depict the course taken by the first header and yellow colour to depict the course taken by the second header, clearly illustrates Mr Buckland's evidence. Unfortunately the reproduction of Exhibit D in the appeal book does not show these colours. The original, however, is quite clear in this regard. 167 Craig Griffiths gave evidence, illustrated by a sketch, Exhibit Y, that the header had taken a different course in the northern paddock. He also testified that Mr Buckland had been with him throughout the whole stripping operation, a period of 3-4 hours. His Honour preferred the evidence of Mr Buckland whom he described as "an alert and discriminating observer whose long experience as a farmer and grazier sharpened his memory on matters close to that experience." He was also satisfied that Mr Buckland had considerable experience in the operating of headers. He also found that Mr Buckland had not invented, with hindsight, the pattern shown on Exhibit D. 168 When Mr Buckland observed the infestation in April 1994, he was of the opinion that its pattern corresponded with the path taken by the second header, in the stripping operation on 3 December 1992. The densest growth of Parthenium weed was in the area where the second header had stripped the southern portion of the crop. The remainder of the infestation, or most of it, followed the path of the second header in the northern portion. Mr Ian Kelly, an expert witness called on behalf of the respondents, the Chief Weeds Officer for Castlereagh/Macquarie County Council and very experienced in the eradication and control of Parthenium weed in New South Wales, lent support to this view. He had observed, in the course of his activities, Parthenium infestations in paddocks in circumstances where it was quite clear that the infestation had arisen from the spreading of Parthenium seeds by a header. In his opinion the pattern of infestation in the 650 paddock was entirely consistent with Parthenium seeds having been spread during the 1992 harvesting operation. Indeed, he stated that, having regard to the spreading propensity of the weed, the whole observable infestation could have been occasioned by the scattering of less than a thimble full of seed at that time. The growth that he observed in April 1994 could readily have been achieved by two cycles of growth and seeding in the affected area. Indeed, his view was that if a further season had elapsed without the implementation of eradication methods, the entire 650 paddock would have been covered with the weed. 169 Other witnesses also supported the view that the pattern of infestation pointed to spreading of seed during the operation of the harvester. Although there was evidence that the seed could be spread in various ways, there appears to have been no significant opposition to the contention that, in the case of the 650 paddock, it was spread by the operation of the second header. His Honour so found. 170 A significant contest in this part of the case was between two hypotheses, the first advanced by the respondents, the second by the appellants. The first was that, as a result of repair work done to the second header in the period of time which elapsed before its joining in the harvesting work, seeds that had previously been secreted in the interstices of the machine were liberated, with the result that they "trickled" out of the machine, whilst it was engaged in the harvesting operation, the bulk of the seeds leaving the machine at the early stages of the harvest in the southern portion and the remainder being liberated slowly as the machine completed its work in the northern portion. The alternative hypothesis was that the seeds that were spread by the harvester were not seeds that had come with it from the infested areas of Queensland, where it had been working, but derived from Parthenium weeds that were growing and in seed amongst the oat crop that was being harvested. These plants, it was contended, were the result of earlier seeding in 1990. The seeds were introduced into the paddock by Mr Weir's vehicles which assisted in the 1990 harvest; if not Mr Weir's vehicles, then other vehicles from Queensland which had been in the area at the time. The second hypothesis, then, accepted that the infestation was occasioned by the operation of the header but asserted that the appellants were not responsible for the presence of the seed that was spread during the harvesting. 171 The first hypothesis was supported by the evidence of Mr George Buckland and his son Martin. Each said that the second header had been stationary near the entrance to the 650 paddock for a period of time before it entered upon the harvesting operation. There was some conflict as to the period, but his Honour accepted that, as already indicated, it was stationary for half an hour to an hour. During that period Mr George Buckland and also his son saw two or three men clambering about the header in ways strongly suggesting that work was being done upon it. Mr George Buckland saw the men about the top of the machine and going inside it. With his knowledge of headers he was of the view that what he observed went beyond activities which might be associated with the mere servicing of the machine. Work of a more fundamental nature was being done. From his observations he was, however, unable to determine what the work was. Nor could his son assist him in this regard. 172 However, a case was sought to be made that repair work had been undertaken prior to the movement of the header into the crop. Indeed, it was asserted that the men who had been observed were engaged in repairing or replacing a crankshaft essential to the operation of the straw walker apparatus and that this exercise was capable of dislodging Parthenium seed which had hitherto been hidden by and kept out of harms way in crevices and behind plates which were necessarily disturbed by the work. Support for this proposition was sought in evidence of purchases made by Mr Schafferius from a local supplier of header parts, appropriate to such a repair operation. 173 This part of the respondents' case failed. His Honour was impressed with Mr Schafferius as a witness. He accepted his evidence that the parts in question had not been purchased for any such specific repair operation but were obtained in order to maintain his stock of replacement parts which was regularly carried with the headers. This finding of his Honour has not been attacked in the appeal. 174 His Honour was, however, satisfied that some work was done on the header by the men observed to be clambering about it but he was unable to determine, on the evidence, what that work was. 175 His Honour rejected the appellants' hypothesis. He did so for a number of reasons. He accepted the evidence of Mr George Buckland, whom he regarded as a satisfactory witness, that the oat crop was sparse and did not impede visibility of the area in which it was growing. He accepted that Mr Buckland could have seen the Parthenium weed amongst the crop if it were present, especially having regard to the height that it would have achieved before it set seed. Moreover, if the Parthenium weeds were present as a result of seeds dropped in 1990, having regard to the seasons between then and April 1992, there would not have been merely a few weeds in 1992 but, more probably, an infestation approaching that which was observed in 1994. Furthermore the 650 paddock had had crops planted, to which reference has already been made. During the preparation of the paddock and the planting and harvesting of those crops, Parthenium weed would have been observed if it were then present, as a result of dropping of seed in 1990. 176 His Honour, also, preferred the evidence of Mr Kelly to that of Mr Chapman, an expert in the operation of headers, who had given, as his opinion, that the amount of infestation observable in 1994 could not be accounted for by seeds that might have been liberated from parts of the header during the harvesting process. The infestation was too large to be accounted for in this way. Mr Kelly, whose expertise in relation to Parthenium weed was clearly superior to that of Mr Chapman, was accepted when he indicated that the amount of seed necessary to cause the infestation in 1994 could very well have come from deposits within the header during the 1992 operation. Mr Kelly had accepted that it was possible for Parthenium seeds to be spread by a header as a result of Parthenium plants being harvested along with another crop. However, he preferred the view that the infestation that he saw in 1994 was caused by seed "trickling" from a header during the harvest. 177 This was consistent with the pattern that he observed, in prior infestations that he had examined, when header operations were clearly implicated. 178 The possibility that Parthenium seed had been sown with the oat crop in 1992 was not accepted by his Honour. The oats had been purchased from a reputable local supplier, there being no suggestion that weed seeds would have been included in his supplies. Also, if Parthenium seed had been harvested along with the oat crop in 1992, it was suggested that some of that seed, however light it was, would have found its way into the collecting bin of the header. That being so it might be expected that when the oats were later sown to produce another crop, Parthenium would also have appeared. This did not in fact occur and was strongly suggestive of the fact that there had been no harvesting of Parthenium at the time when the oats were harvested. 179 His Honour also rejected the proposition that the Parthenium infestation in 1994 could have resulted from the operation of Mr Weir's trucks. Although those trucks might have carried Parthenium seeds from Queensland they were not, on the evidence operating in the area where the Parthenium infestation occurred. Their operations could not have produced a growth of Parthenium which might have been harvested along with the 1994 oat crop. 180 His Honour, therefore, rejected the appellants' hypothesis and partially rejected the respondents'. He remained, however, "satisfied, on the balance of probabilities, that Parthenium seed was brought and distributed on the 650 paddock by a header belonging to the first defendant on 3 December 1992." There remained, for consideration, the question whether "the release of the seeds was a result of some breach of duty" on the part of the appellants. 181 His Honour, after excluding certain heads of negligence, which had been pleaded by the respondents, focused attention upon the significance of the work observed to have been in progress on the header, before it was introduced into the crop. It is convenient to quote the following extract from his Honour's judgment in this regard: "I accept that no act of changing a part on the header was proved but this absence of proof of a specific act does not exclude the plaintiffs from relying on an inference that if the header spread seed it could only have happened if work of some kind was done on the header before it commenced work on the paddock and in the course of that work Parthenium seed was dislodged. Witnesses gave evidence that a John Deere 9600 contained a number of parts in which debris could become trapped and hidden in such a way that even a thorough cleaning of the kind carried out by the Schafferius outfit would not necessarily remove it. If the seed was to be dislodged and blown out of the back of the machine but not find its way into the grain bin, it is more likely that it was trapped in areas such as the straw walkers or rear axle. The latter was singled out for particular emphasis by Mr Ivan MacDonald in his written statement with accompanying photographs (Exhibit U). In his written statement (Exhibit N) Mr Kenneth Chapman, a contract grain harvester of thirty years experience, identified failure of a walker crank as the mechanical problem which actually required attention and which had been the source of the Parthenium seed which was later distributed on the 650 paddock. However, it was clear from Mr Chapman's oral evidence that he had been led to this particular conclusion by reports circulated at the time of what had occurred on the Buckland's property. His evidence therefore does not establish the actual location of the Parthenium seeds but it does identify one other location on a John Deere 9600 where Parthenium seed could be trapped and later dislodged if work of that kind was done on the machine. There were, I am satisfied, a number of places on the John Deere 9600 where seed could have been trapped sufficiently to avoid removal when the machine was cleaned but capable of dislodgment when released by removal of, or interference with some part. Some such parts were situated in areas where the seed once dislodged would not necessarily find its way into the grain which had been harvested but could be blown or shaken off the machine as it was working the paddock. Mr Alistair Henderson, the author of the Taylor Byrne Report On the Outbreak of Parthenium Weed (Exhibit 12) conceded in cross-examination that material lodged in cavities in headers might be loosened by probing the cavity with a piece of straw. Such material could be loosened if "hit with a hammer or bumped or pushed apart". 182 His Honour then turned to consider the standard of care that should be imposed upon the appellants. He considered the principles expounded in Burnie Port Authority v General Jones Pty Limited (1994) 179 CLR 520 which were relied upon in the respondents' statement of claim. He noted that the majority judgment, whilst abolishing, for Australia, the rule in Rylands v Fletcher, pointed out that the standard of care in negligence varied with the magnitude of the risk of an accident and the seriousness of its potential consequences. He noted that the Bucklands relied upon the following statement in the judgment: (179 CLR 520 at 554). "… Depending upon the magnitude of the danger, the standard of "reasonable care" may involve "a degree of diligence so stringent as to amount practically to a guarantee of safety". 183 Reference was then made to the significantly dangerous qualities of Parthenium weed and the serious consequences to a property owner of an infestation, which could result in the infested area being taken out of production for many years with a significantly deleterious effect upon the value of the whole property. He also emphasised the fact that Mr Schafferius, coming from a heavily infested part of central Queensland and having such an infestation on parts of his own property, was well aware of the magnitude of the risk of spreading the seeds. His Honour then stated: "There was, in such circumstances, an especially high standard of care imposed on the defendants to prevent the contamination of land in New South Wales from seed carried on their harvesting machinery. This included steps to ensure that no work was done on the machinery once in New South Wales which might dislodge Parthenium seed not removed by ordinary cleaning processes, or if such work was undertaken, steps would be taken to destroy or sterilise any dislodged Parthenium seed." 184 His Honour then made the following findings: "I am satisfied that work of some kind was done on the second header on the morning of 3 December, 1992 before the header proceeded to assist in the completion of the stripping of the 650 paddock and that in the course of that work, Parthenium seed was dislodged and subsequently spread as the header worked the paddock. I find that there was negligence on the part of the employees of the defendants, in failing to take adequate steps to prevent the escape of Parthenium seed from the header, having worked on the header." 185 His Honour then made reference to a pamphlet which was in evidence before him. It was issued by the New South Wales Government and was entitled "Clean Your Header - Keep NSW Parthenium-Free". The pamphlet listed nineteen separate points on a header which should be checked in the cleaning operation for the removal of noxious weed. He noted that the evidence established that Mr Schafferius had, in the cleaning operation at Mungindi, attended to the nineteen points. However, there was a further requirement in respect of ten of the points that they "must be thoroughly sprayed with diesel to sterilise weed seed material that may be trapped in cavity areas". There was no evidence that this requirement had been complied with either at the border or thereafter. Although his Honour does not make specific mention of this, his finding that unsterilised seed was spread from the header would indicate, clearly enough, that this precaution had not been taken. 186 His Honour, accordingly, found Katena, and Messrs Shafferius and Sawley, liable to the plaintiffs in negligence. 187 Before considering the case brought against the first appellant, the State of New South Wales, his Honour's decision, and the appeal from it, it is convenient to consider the appeal against the decision that I have just considered.

The appeal of Katena and Messrs. Shafferius and Sawley 188 It was asserted in this appeal that, in the event of causative negligence being found, only Katena and not Messrs. Shafferius and Sawley could be found liable to the respondents. I shall return to this ground. On the issue of negligence, an attack was made on his Honour's finding that the seed spread by the second header on the 650 paddock was seed carried in the machine from Queensland. It was asserted that the appellants' hypothesis that the seed came from Parthenium weed already growing in the oat crop was at least as likely to be correct as the appellants' hypothesis, in which case the appellants were entitled to a verdict ( Luxton v Vines (1951-52) 85 CLR 352). It was also submitted that, even if it was Queensland seed that came from within the machine, there was no evidence that its dispersal resulted from any negligent act or omission on the part of the appellants. 189 In relation to the first submission the same arguments were put to this Court as had been put to his Honour, perhaps with some changes of emphasis. 190 An attack was made upon what was described as the "trickle" theory. The term came from the evidence of the expert witness Mr Kelly. As already noted, he explained the pattern of infestation on the basis that seed "trickled" from the machine during its harvesting operations. The term was used in conjunction with his evidence that very few Parthenium seeds would have been needed to produce the high degree of infestation visible in 1994. 191 It is unfortunate that the term was not more closely defined in the evidence. A reading of Mr Kelly's testimony, written and oral, does not produce a clear picture of how the trickling occurred; in particular, whether the term was meant to convey that small amounts of seed would drop to the ground from the interstices of the machine, from one or more of the many places where it could have been trapped, by some unexplored route, or whether the seeds, being extremely light, would, from time to time, be emitted from the machine by way of the air blast which dispelled, from the back of the machine, unwanted products of the threshing operation. However, I do not accept that this difficulty destroys the overall effect of his evidence. 192 His thesis appears to me to be that cleaning procedures, sufficient to permit a header to pass from Queensland into New South Wales, even if they conform to "best practice" cannot remove all Parthenium seed. The seed can lodge in crevices and behind plates and in other inaccessible areas where cleaning procedures will not reach it. From those areas it can be dislodged by work done in their vicinity. Once dislodged, it can be dispersed from the machine whilst the machine is stripping. A very small quantity of seed so emitted is capable, in the right conditions, of germinating and producing a plant which through rapid growth and setting of seed can swiftly cause an infestation. Although it is apparent that he relied to some extent on information provided to him by Mr Buckland, as to a particular repair having been effected to the header before it commenced to operate, I am satisfied that his evidence does not stand or fall on the substantiation of that information. His evidence is too general to be tied to one hypothetical repair operation. Indeed, in answer to the question as to how much work would have to be carried out on a header to disturb seed he answered that "it could be the smallest amount of work or it could be a major job." I am satisfied that the effect of his evidence is that once even a small amount of Parthenium seed, previously trapped within the machine, was dislodged, then it could be emitted from the machine whilst it was in operation at various times during the course of its work. The dislodging could be caused by work within the machine of varying kinds. This evidence accords with other evidence in the case, particularly that of Mr McDonald to whose evidence his Honour made reference in the passage cited. In my view, the attack on the "trickle" hypothesis failed. It is based upon an erroneously narrow interpretation of his evidence. 193 It was also submitted, as I understand it, that the "trickle theory" was unsustainable because the bulk of the Parthenium infestation in 1994 was in the small southern section. It was put that the trickle theory could not account for a greater infestation in this area as against the significantly smaller areas in the northern section, the consequence being that it was more likely that undetected Parthenium weeds were harvested in the southern section and the seeds disbursed almost immediately. I can see no substance in this submission. The "trickle theory", despite its unfortunate terminology, does not, in my view, on a fair reading of the evidence, require that there be a methodical and measured emission of seed. Where a dislodging has occurred which is amenable to the air blast of the machine in operation, there is nothing to suggest that the whole of the dislodged seed would be removed from the machine at the one time. Mr Kelly obviously accepts that the more intense infestation in the southern section and the smaller infestation in the northern section could be accounted for by the dislodging of seed within the machine and its subsequent spreading in varying amounts. 194 It is undoubtedly true that the respondents' case would have been assisted by a more detailed exposition of the way in which Parthenium weed, when dislodged from places of entrapment in the machine, could be expelled from it. However, in my view, there is adequate evidence to establish that it is more probable that the seed came from within the machine, from places whence it had been dislodged, rather than that seed had been harvested from the paddock during the stripping operation. 195 In my view, his Honour was quite correct in rejecting the "harvesting" theory. On the evidence, it is virtually inconceivable that Parthenium seeds introduced from vehicles, other than the appellants' and Mr Weir's, during the 1990 harvest, could have produced Parthenium weeds concealed amongst the sparse oat crop in 1992. The paddock was put to crops twice thereafter, without any sign of the weed. With its capacity to spread it would surely have been very much in evidence before 1992. Moreover his Honour accepted Mr George Buckland's evidence as to his observations in 1992 as detailed in Exhibit D. The effect of his evidence is that the Parthenium outbreak found in 1994 followed the track of the second header. If there had been concealed Parthenium weed in the oat crop it would be most unlikely that the first header would not, also, have inadvertently harvested some of it, with the result that the later infestation would have also followed in its tracks. On the basis of Mr Buckland's evidence, as accepted by his Honour, this did not happen. 196 I am satisfied that the "harvesting" theory does not share equal probability with the "trickle" theory. This ground of appeal must fail. 197 I turn then to the next attack made on his Honour's decision, namely that the evidence fails to establish negligence on the part of the appellants. This raises more difficult questions. 198 The respondents' case on negligence was founded upon the performance of work upon the second header prior to its entering upon the stripping of the oat crop. His Honour was unable, on the evidence, to determine what work had in fact been done. Moreover, an attempt by the respondents to establish the performance of a particular repair, based upon the purchase by the appellants of particular spare parts, as has been seen, failed. In these circumstances it is and, no doubt, was the submission of the appellants that no finding of negligence can be made. If it could not be established that the appellants' employees were performing particular activities in and upon the header then there was no basis for the attribution of negligence. Also, if those activities were unknown, it was impossible to attribute foreseeable risk to their performance or to enter upon a consideration of what reasonable steps might have been taken to prevent the risk eventuating. 199 His Honour clearly did not accept these arguments and, in the passages set out above, found negligence in the manner and for the reasons that he gave. Was he correct in so doing? 200 Obviously, his Honour did not have before him evidence of the kind referred to above. It is important, however, to consider what he did have. In the earlier passage cited above that material is stated in compendious fashion. It is convenient, however, to refer to some of the evidence as it was actually given. This evidence, of course, needs to be considered against the background that the second header contained within it Parthenium seeds transported from its work in Queensland and which had not been emitted from the machine during the course of any of the prior work done by it in New South Wales, including work done on other crops of the respondents in November/December 1992. Logic demanded that there be a reason for its dropping of Parthenium seeds during the harvesting of the oat crop on the 650 paddock and only during that harvesting. 201 The evidence relating to the performance of work on the second header comes from Mr George Buckland and his son Martin. Evidence called by the appellants was quite unhelpful. The witnesses had no relevant recollection. Although there was some confusion between Messrs. Buckland Senior and Junior as to the time during which the work was carried out, it is clear that his Honour, having of course observed them in the witness box, was prepared to accept their evidence as basically accurate. 202 Mr George Buckland said that the second header took longer to come to the crop because "they were doing something to it." He observed "men clambering up all over it and in it near the top." Later in his evidence he said "I didn't go close but they were definitely working on the header" and that "they weren't down underneath it or anything, they were near the top and inside it and at the front of it high up." Later he indicated that the straw walkers went "right to the top." He also said that what was being done on the header "just wasn't the normal thing." 203 Mr George Buckland was an experienced header operator and knew the working parts of the second header and how they operated. In relation to the emission of the Parthenium seeds from it he gave as his opinion that "all that seed was right on top of the straw walkers and it walked out and the air going under it never let it come down onto the riddle box, so it didn't get into the grain." (By this he meant the harvested oats.) 204 In further cross-examination he was asked where he said the Parthenium seed came from and he responded that it came from the top of the header. The following exchange then took place: "Q. The top of the header? A. Inside, the straw walkers.

Q. But Mr Buckland, the headers had been working flat out for some weeks cutting wheat and other crops? A. Well do you want me to tell you just how I think it came?

Q. Yes? A. Well I've driven headers for a jolly long time and straw walkers have the habit of packing up with straw not as much as they used to but they'd pack up with straw.

Q. Whereabouts? A. On top of them. Have you ever seen the straw walker?

Q. Yes, we'll be having a look at one of these John Deere's? A. The straw walkers have got whole lots of, its slats across it and sometimes they pack up with straw, especially on the front and then as well as straw the seed, any foreign seed would pack up in there too.

Q. I see right? A. Now my thought is that that header, they were doing something to it and--

Q. You don't know that they were doing…(not transcribable).. A. They took a long while doing it.

Q. All right. A. And some joker might have just got hold of that bit of straw and pulled it out and left it there, that's what I reckon.

Q. Left it where? A. On top of the straw walkers. Q. Now if he didn't do that, what does that do to your theory? A. If he didn't do that well they could have loosened it when they were doing something to it."

Later he said that he thought the Parthenium was in the compacted straw in the straw walker because "it was up near the top like that because it didn't get into the seed." 205 When asked whether he would agree that it was highly unlikely that compacted straw containing Parthenium weed would remain stuck in the straw walker through the whole process of cleaning and the harvesting thereafter of ten or twenty properties from the Queensland border to Coonamble, he said that he did not agree and that it could stick there "because I've seen it happen. Especially if they harvested any summer crop because it is more likely to pack in straw walkers, sometimes it's a bit green." 206 Mr Buckland also advanced the theory that there were other parts on the top of the machine where the Parthenium seed could lodge. These were panels behind which seed could lodge and "until you take them apart it doesn't come out." He further said "it doesn't come out if the header's been cleaned but it's still there until you take them apart." He expressed the view that something had been taken apart because of "the pattern of the header." He agreed that he hadn't seen the men taking anything apart but that the length of time the men were working on the machine indicated that "it wasn't just ordinary service." 207 A reading of Mr George Buckland's evidence conveys the clear impression that he regarded the activities which he observed, over at least half an hour, on the header as being out of the ordinary, not merely routine servicing before commencement of work but amounting to the fixing of something inside the header near the top, as a necessary preparation for stripping the oat crop. He did not know what was being done but raised possibilities based upon his experience with headers and his knowledge of the operation of the machine. 208 I have already made reference to the evidence of Mr Kelly. The evidence of Mr MacDonald, referred to in the passage cited from his Honour's judgment, demonstrated with the aid of photographs a number of areas in a John Deere 9600 header where, despite cleaning, seed could be concealed and dislodged if parts were subsequently disturbed or removed. Mr Martin Buckland gave evidence as to a possible removal of material from the straw walker. He said that in the course of working from the border it could have straw all through it which could lead to the pulling of that straw which may have produced the problem. The removal of that straw could also remove what might have been left there after the cleaning operation at the border, that material containing Parthenium seeds. 209 It is clear, then, that the respondents' evidence contained opinions, based upon experience, and expert knowledge, as to how concealed Parthenium seed could be liberated by work carried out inside the header, particularly in the straw walker area near the top. Apart from the repair work suggested but specifically negated, there appears to be no evidence in the case suggesting that the type of work, the subject of these opinions, was not or could not have been carried out during the activities observed by Mr George Buckland. Indeed Mr Shafferius himself agreed that the walkers constituted an area where debris packs down producing a need "to go in and loosen things up with a screwdriver…because there is little bits and pieces in it stuck." 210 In my view there was evidence before his Honour to found an inference that the Parthenium seed was distributed in the 650 paddock as a result of the work done by the men observed by Mr George Buckland to be clambering about the machine before it commenced to strip. This was outside the area of mere conjecture because the doing of some work in the relevant part of the header had been clearly observed. The inference was also clearly open that it had not commenced work in association with the first header from the outset because it was necessary that work be done on it before it could start stripping. Whatever the work was it resulted in the dislodging of hitherto concealed Parthenium seeds so that they were liable to be emitted from the machine once it was put into stripping operation. It was not possible, of course, in the circumstances for direct observational evidence to be given of the actual work. However, the opinions that were given as to what that work might have been, apart from the failed repair theory, were not negated by evidence from the appellants. 211 In my view, it would have been open to his Honour, in the circumstances, to draw the inference, which would, in the circumstances, be more than mere conjecture, that work was done which involved clearing impacted straw from the slats of the straw walker, which then liberated concealed Parthenium seed. Having regard to the fact that the work was being undertaken in an area where the seeds, if emitted from the machine, could germinate and lead to the sort of infestation of which the operators, coming from the state of Queensland, would have been well aware, his Honour could have found that the doing of the work carried a risk which was far from fanciful. That being so, the work should not have been undertaken in the area where it was, or only with suitable precautions. One such precaution, clearly accepted by his Honour on the evidence, was to spray the areas of risk with diesolene. Having regard to the infestation that occurred it is clear that this available sterilisation procedure was not carried out. 212 In my view, his Honour could have reasoned through to a finding of negligence along these lines. His Honour, however, did not need to do so, as he approached the matter on the basis of the principles expounded in Burnie Port Authority v General Jones Pty Limited (1992-1994) 179 CLR 520. In that case the majority in the High Court subsumed the rule in Rylands v Fletcher into the general law of negligence, indicating that in circumstances where that rule had previously applied, the justice of the case could be met by imposing a very high standard of care upon the defendant. The relevant passage appears in the judgment of the majority (Mason CJ, Deane, Dawson, Toohey, Gaudron JJ) at page 554. It reads as follows: (His Honour cited part of it in his judgment). "Where a duty of care arises under the ordinary law of negligence, the standard of care exacted is that which is reasonable in the circumstances. It has been emphasized in many cases that the degree of care under that standard necessarily varies with the risk involved and that the risk involved includes both the magnitude of the risk of an accident happening and the seriousness of the potential damage if an accident should occur. (See, e.g., Thompson v Bankstown Corporation (1953) 87 CLR at 645, Wyong Shire Council v Shirt (1980) 146 CLR 40 at 47-48). Even where a dangerous substance or a dangerous activity of a kind which might attract the rule in Rylands v Fletcher is involved, the standard of care remains "that which is reasonable in the circumstances, that which a reasonably prudent man would exercise in the circumstances" ( Adelaide Chemical & Fertilizer Co Ltd v Carlyle (1940) 64 CLR at 523, per Starke J; and, generally, Stevens v Brodribb Sawmilling Co Pty Ltd (1986) 160 CLR at 30, 42). In the case of such substances or activities, however, a reasonably prudent person would exercise a higher degree of care. Indeed, depending upon the magnitude of the danger, the standare of "reasonable care" may involve "a degree of diligence so stringent as to amount practically to a guarantee of safety. ( Donoghue v Stevenson [1932] AC at 612, per Lord Macmillan; Adelaide Chemical & Fertilizer Co Ltd v Carlyle ( 1940) 64 CLR at 523, per Starke J; and generally Stevens v Brodribb Sawmilling Co Pty Ltd (1986) 160 CLR at 30, 42). 213 I think that it is clear from his Honour's judgment that he regarded the case as one requiring a standard of care involving "a degree of diligence so stringent as to amount practically to a guarantee of safety." I am not prepared to find that his Honour was in error in so doing. One has only to recall the dangerous qualities of Parthenium weed and its capacity to spread, as evidenced not only by the rapid degree of infestation apparently in the present case but, more significantly, by the quite enormous area of infestation in the state of Queensland, to regard the seeds as being seriously hazardous in themselves. The evidence, clearly enough, indicates that the introduction of the weed onto someone's property is quite disastrous. The use of the property is severely restricted for many years until it can be positively proved that the weed has been eradicated. The value of the property is severely diminished. Indeed the expert witness Mr Kelly indicated he would never buy a property affected by the weed. 214 The evidence in the present case clearly indicates that Messrs Shafferius and Sawley, coming as they did from an infested area in Queensland, would have been well aware of the serious danger involved in the spreading of the seeds. Also they would have been fully aware that even "best practice" cleaning procedures could not remove all the seed from the headers. They would also have been aware that interference with areas of the header where Parthenium seeds might be lodged, immune from the cleaning process, could lead to the liberation of seed into the outside world through the operation of the header machinery. The evidence established that dislodging of the seed could occur in a number of ways by work done in the machine. In my opinion, his Honour was correct in holding that the standard of care in the circumstances was such as to require that no steps be taken which might have that effect unless they were accompanied by other steps which would neutralise the deleterious effect of the seeds. Such a step could be the effective spraying of the dislodged material with diesolene. Two things are plain: (a) seed was dislodged by the work, whatever it was, undertaken on the second header before it commenced stripping and (b) seed was not sterilised before it was emitted from the machine. 215 I am satisfied, that, in these circumstances, his Honour correctly found that there had been a breach of the duty of care owed to the respondents. In these circumstances, I do not find it necessary to consider the submission sought to be raised by the respondents in their notice of contention. 216 There remains the question whether his Honour was in error in finding all three appellants liable to the respondents in negligence. 217 This question was dealt with in a fairly perfunctory way in written submissions from both the appellants and the respondents. There had been some submissions made to his Honour on the question of liability of the three appellants in relation to the claim in contract. His Honour dismissed the claim in contract and, as previously indicated, this has not been the subject of appeal. In relation to that claim however he did make some findings as to whether Katena was an undisclosed principal in the contract. There is no need to consider them. In relation to the claim in tort his Honour made the following findings: "Although there is no direct evidence that Peter Schafferius, Dean Sawley, Mark Sbresni, Craig Griffiths, Bart Simpkins or any of them were employed by Katena Pty Ltd this seems to have been assumed by both sides and on that assumption Katena Pty Ltd, as first Defendant would be liable for a breach in the course of employment by all or any of them in the tort of negligence." 218 His Honour obviously proceeded on the basis of this assumption. It has not been submitted that he was in error in making it, having regard to the way in which the trial was conducted. In my opinion the assumption should not now be questioned in this appeal. 219 Accordingly, in my view, for the reasons I have given all three appellants should be found liable in negligence to the respondents. Their appeal should therefore be dismissed.

The appeal of the second defendant 220 The second defendant, the State of New South Wales, was sued for breach of statutory duty and also for negligence in acting in the exercise of a statutory power. The first claim failed and has not been the subject of appeal. With regard to the second claim the relevant statutory powers are found in Clause 6 (4) of Ordinance 50 made under the provisions of s 475J of the Local Government Act 1919 Part XXII. Clause 6 (4) deals with the requirements for border inspections in relation to the permitted entry into New South Wales of "any prescribed agricultural machinery." It provides as follows: "(4) A border inspector shall inspect a prescribed agricultural machine produced for inspection under subclause (3) and shall issue a permit only if - (a) where the border inspector suspects that Parthenium weed is or may be present on or in the machine, the person seeking the permit treats the machine, in accordance with the border inspector's directions, so as to remove any Parthenium weed to the satisfaction of the border inspector; (b) the border inspector is satisfied that the machine is free of Parthenium weed; or (c) the border inspector is of the opinion that, in the special circumstances of the case, it is proper to issue a permit." 221 His Honour found (without difficulty) "a lack of sufficient care on the part of the second defendant in the conduct of border inspections generally and in the inspection carried out on the first defendant's headers at Mungindi on 9 November 1992." The evidence clearly established that the border inspector spent quite insufficient time in the making of an inspection. Additionally, he had never seen a Parthenium seed, had no experience of headers and did not have any knowledge of their internal mechanisms. His Honour's finding is plainly correct. 222 The real question however, was one of causation. His Honour accepted that "The plaintiffs must prove that a careful inspection, up to the standard reasonably to be expected, would have discovered the seed and prevented its transportation into New South Wales. This is without doubt the most difficult aspect of the case against the second defendant as far as the plaintiffs are concerned." 223 His Honour dealt with the matter as follows: "Since there is no evidence of where, on the header, the seed was trapped, nor of how it was dislodged, it is impossible to say in what particular respect the inspection needed to have been improved in order to locate the seed. However, that is not the end of the matter. The seed was dislodged in the course of work done on the machine which took somewhere between one half and one hour. It is most unlikely that the work involved the dismantling of the machine beyond that which a reasonably thorough inspection process would have required. It is therefore more likely than not that a thorough inspection, sufficient to meet the high standard which the danger of infestation and the second defendant's own policy of eradication required, would have uncovered the seed which was subsequently dislodged by employees of the first and third defendants." 224 I am, with great respect, unable to agree with this finding. The machine had been, as his Honour found, sufficiently cleaned, to "best practice" standard. This had not been sufficient to remove the Parthenium seeds which later caused the problem. It is not possible, in my view, to take the step involved in his Honour's finding without an evidentiary basis to establish what level of inspection would have been required to ascertain the existence of the seed concealed in the machine. If it be accepted, as I think it must be, that the Ordinance did not require an inspection, based upon the Western Australian approach, calling for the entire dismantling of the header, then it would follow that a reasonable level of inspection could not guard against the possibility that seeds trapped in inaccessible areas might not later be liberated as a result of work done on the header in the course of its operations in New South Wales. The doing of such work and its consequences would, in my view, effectively break the chain of causation. 225 In this regard, I have had the advantage of reading, in draft, the reasons for decision of Rolfe JA. I respectfully agree with what his Honour has written and adopt his reasons. 226 By a notice of contention, it was submitted on behalf of the respondents that Ordinance 50 must be read in such a way as to give effect to the duty said to reside in the State of New South Wales to protect its citizens from the introduction of Parthenium weed in the state. So read the Ordinance "could only be complied with by using all available means of removing the weed," and the concept of "reasonableness and performance of a duty would not exclude the application of the Western Australian inspection standards." It was further put that if it was not practicable to clean all Parthenium from the Queensland headers they should have been forbidden entry to New South Wales. 227 I am unable to read Clause 6 (4) of Ordinance 50 as providing any such limitations on a border inspector's discretion to issue a permit. It may be that, having regard to the highly dangerous nature of Parthenium, the State should impose a regulatory ban on the introduction into New South Wales of agricultural machinery which has operated in the infested areas of Queensland. However, the State's legislative response to the problem by way of Clause 6 (4) falls well short of taking such a step. 228 I consider, therefore, that the appeal of the State of New South Wales should be upheld. 229 I would refrain, at this stage, from making any cost order in respect of the upholding of this appeal, as it may be that a case could be made for the making of a Bullock or Sanderson order in favour of the respondents. No submissions have been made in this regard. I propose that a reasonable opportunity be allowed for the making of them, should this be desired.

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