VIP Plastics has successfully sued BMW Plastics for infringing its patent for a “Variable-length Dip Tube for a Fluid Transfer Container”. The most interesting point to emerge is why the expert evidence on one side prevailed and, on the other, failed – even so far as being rejected as inadmissible.
How the battle was won
As is typically the case, much of the battle turned on whether applicant’s expert evidence or the respondent’s was accepted. Kenny J denied that the respondent’s expert’s evidence was not admissible and, even if it were, would have preferred the applicant’s witnesses. The applicant’s witnesses were the named inventor and his assistant.
In construing a patent (whether for deciding its validity or if it has been infringed), it has to be read through the eyes of the (non-inventive) person skilled in the art.
Who is the person skilled in the art
Kenny J found at  that the relevant field or art in this case was:
the manufacture and use of dip tubes, particularly in chemical transfer drums or like containers used in the agricultural and veterinary fields.
The named inventor gave evidence about the attributes of the person skilled in this art at :
these attributes included a good working understanding of the processing of plastics and the manufacture of plastic products (involving, amongst other things, an understanding of varying grades and types of plastics and manufacturing processes such as extrusion and blow, injection and vacuum moulding, as well as the economies of such processes). According to Mr Mandile, it was also necessary to have some experience and understanding of the manufacture of large plastic fluid containers (of a size more than 20 litres in volume) incorporating some sort of extraction system. Further, it was necessary to have an understanding (of the kind that a chemical engineer would have) of the environmental stress effects on plastics and the performance characteristics of varying grades of polymers under stress and when interacting with the types of chemicals solutions used in agriculture and likely to be stored in the drums. Finally, it was necessary to have some familiarity with the various products and solutions that had been tried in the industry. In Mr Mandile’s opinion, knowledge of this kind was generally confined to people working in the plastics industry, who had experience in the design and processing of plastic containers of larger sizes and the manufacture of plastic packaging and transfer of chemical fluid to and from such packaging. In cross-examination, Mr Mandile stated that he regarded himself as a person skilled in working in the field of dip tubes for agricultural and horticultural purposes.
Kenny J noted that Aickin J had accepted that evidence about the experiments undertaken by an inventor leading up to the invention could be relevant even if “not always likely to be helpful”. As a result, Kenny J considered at  that the inventor could also give evidence about the characteristics of a the person skilled in the relevant art, albeit such evidence needed to be assessed carefully. On the other hand, the respondent contended that “just about any engineer with a basic knowledge of manufacturing techniques and a basic knowledge of mechanics of devices could be classified as a skilled addressee”. Kenny J rejected this on the evidence.
Accordingly, her Honour accepted at  that:
the skilled addressee is a person with practical knowledge of and experience in the manufacture of plastic products, particularly large fluid containers incorporating some kind of extraction system. That is, such a person would have practical knowledge and experience in the manufacture of plastic packaging for the storage of fluid and the transfer of such fluid from the packaging. Such a person would also have an understanding of the environmental stress effects on plastics.
Why the professor was not a psa
There were a number of problems why Kenny J considered that the evidence of the professor advanced by the respondent was not relevant (and so not admissible). The chief reason was that he had no relevant or special expertise and was unable to give evidence about what those in the art would know or do.
Section 76 of the Evidence Act generally rules opinion evidence inadmissible. One important exception is provided by s 79 for “expert” opinion (about a relevant issue). The opinion is “expert” for this exception where it is evidence from a person if the person “has specialised knowledge based on the person’s training, study or experience” and the opinion “is wholly or substantially based on that knowledge” (emphasis supplied).
In this case (and will not necessarily be true in every case), the professor had worked in the wool industry “for 10 years in the 1980s” and, since then, he had “mainly been an academic, teaching in the area and consulting in minor ways for engineering” when the priority date for the patent was in 2000. Then at :
Of course, in a case such as this, a court may receive expert evidence from persons other than skilled addressees if it is otherwise relevant. There was, however, a serious difficulty with [the professor’s] evidence in another respect: it was not just that he was not a skilled addressee but that he had no history of working in the fields of dip tubes or plastics, or some related field. Without this specialised knowledge, based on training, study or experience, [the professor] was not in a position to give relevant evidence to the court bearing on the meaning of the VIP Patent or a prior publication, the issue of novelty and the issue of obviousness:
Then, so far as the professor gave evidence about the innovation process based on his specialised knowledge, it was not knowledge relevant to the art in question.
There were other problems too: opinions were expressed about questions of mixed fact and law – e.g. it was obvious – based on misunderstanding of key legal concepts; there was also a problem of hindsight.
The use of relative terms
The infringer’s attack on the patent as lacking clarity because it used relative terms such as “inhibits bending” and “just below the end” were dismissed. Kenny J accepted that they were not precise, but found they applied Nesbit Evans Group Australia Pty Ltd v Impro Ltd (1997) 39 IPR 56 at 95 to find they provided a workable standard.
VIP Plastic Packaging Pty Ltd v B.M.W. Plastics Pty Ltd  FCA 660
An earlier round in the dispute where Kenny J refused to refer the matter to the Commissioner by a direction under s 97(3) of the Patents Act.