Tuesday, May 24, 2011

The promise of the patent: “It’s a strange word to me. . .”

Pfizer Canada Inc. v Mylan Pharmaceuticals ULC / donepezil (NOC) 2011 FC 547 Hughes J

The interesting issue raised by this case is the conflict between two views of patent construction. The English Court of Appeal has recently said that “[t]he task for the court is to determine what the person skilled in the art would have understood the patentee to have been using the language of the claim to mean” (Virgin Atlantic [2009] EWCA Civ 1062 at [5]). In contrast, the Federal Court of Appeal has equally recently said that “[t]he construction of a patent is a question of law to be determined by the Court, with the assistance of persons of ordinary skill in the art to which the invention relates” (Bridgeview Manufacturing 2010 FCA 188 at [9]). Both of these statements are supported by ample authority, and taken in isolation either might seem anodyne. Yet in practice there is a serious unresolved tension. On the first view, the construction of the patent is a matter of fact, and the meaning of any term or passage must be established by evidence of expert witnesses. On the second approach, construction of the patent is a mixed question of fact and law, and legal arguments and principles are needed to supplement the expert evidence. In the Pfizer v Mylan / donepezil Hughes J comes down firmly in the latter camp. The case illustrates this wisdom of that position. The practical implication, it may be hoped, is that it may no longer be necessary to advance legal argument via expert witnesses.

The patent at issue in this case claimed the compound donepezil and the use of donepezil as a therapeutical composition for treating senile dementia [191]. The sole question was whether those claims were invalid for lack of sound prediction. In Canadian law utility is measured against the promise of the patent. It is not enough that a claimed invention have utility sufficient to uphold a patent; it must have the utility to the extent promised in the description, even if that promised utility goes beyond what is needed to support a valid patent. I have criticized this doctrine in a previous post, but the important point for present purposes is that the construction of the promise of the patent, not just the construction of the claims, becomes a crucial issue. So, in this case Pfizer argued that the promise was only a compound that could serve as an AChE inhibitor (the mechanism of action) [52], while Mylan argued that it promised a list of specific advantages, such as “excellent effect” with respect to disturbance of memory [Annex]. Hughes J ultimately concluded that the promise was only that it was “effective” for the treatment of Alzheimer’s [232]. He then concluded that this promise was met.

More important than the conclusion is the way in which the battle was fought. The question of whether the various statements in the description amounted to a “promise” and or merely a “hope” or “advantage” was debated through the evidence of expert witnesses (e.g.[77], [113], [167]). That approach was premised on the view that the task for the court is to determine what the person skilled in the art would have understood the patentee to have meant. In this case, the result of treating the question of the promise of the patent as a question of fact verged on the absurd. It was abundantly clear from the evidence, particularly that of Mylan’s main expert, Dr. Becker, that the expert witnesses did not have an independent conception of the legal term “promise” until instructed as to its meaning by counsel. As Dr. Becker stated,

[Mylan’s former counsel] said to me ‘Is this a promise to you?’ I had to read it and I had taken it as a statement, just that they were saying it. I was sort of taken aback by it. Then she asked me if that was a promise, and I said, ‘I guess it is a promise.’ . . .I took a pretty straightforward, stupid approach to it. . . [168-69]

Similarly, an expert for Pfizer stated that the compound claim “contains no promise” [112].

The cause of the problem is that in fact a patent is a document both drafted in a collaboration between an expert in the art and lawyers, and it is read the same way. Just as a lawyer will not understand the meaning of a technical medical term like “acetylchlolinesterase” without the aid of an expert, an expert will not understand the meaning of a technical legal term like “the promise of the patent” (or “comprising”) without the aid of a lawyer. The Court of Appeal in Virgin Atlantic got around the problem by noting at [15] that

it would unrealistic – indeed perverse – for the law to say that the notional skilled reader, probably with the benefit of skilled advice, would not know and take into account the explicit drafting conventions by which the patent and its claims were framed. . . . A real skilled man reading a patent which, as in the case of the Patent, refers to "the parent application" would surely say "what's a parent application?" – and he would go on to ask a man who knows, probably a patent agent.

This solution to the problem raises both conceptual and practical difficulties.

Conceptually, the English Court of Appeal maintains the fiction that the patent is interpreted solely by the posita. Jacob LJ went on to say at [16] that “[i]t follows that we need to address what the skilled man would actually make of the two explicit drafting rules.” But it remains artificial to say that the question is really simply one of fact as to what a posita would think. In Pfizer v Mylan / donepezil, Dr. Becker was asked whether a demonstration of utility has to be in the patent. He answered that “there are legal subtleties to that, and those I did not want to know, particularly” [221]. Does this mean this legal doctrine is irrelevant to the construction of a patent because as a matter of fact, a posita, even one intimately involved in litigating the patent, would not appreciate it? To assume that the posita’s knowledge of drafting conventions amounts to that of a lawyer is contrary to fact, and if we make this assumption as a matter of law, then we might as well simply abandon the fiction that the claim is addressed solely to a posita.

Practically, the result of supposing that the posita reads the patent with counsel at their shoulder is that it is not really the understanding of the posita that is at issue. At best, it is the combined understanding of the posita and counsel; and at worst, the argument of counsel expressed through the expert. As Hughes J noted, “It is very tempting for lawyers to seek to put words into the mouths of experts and then seek to urge upon the Court that these words be accepted as being assistance from the expert in interpretation of a patent” [224].

Thus it is wrong to say that the patent means what a posita would understand it to mean. The better view is that the expert witnesses must assist the court. As Hughes J stated:

[218] As discussed in the foregoing topic, the Courts have made it clear that the assistance of an expert is often required in considering the promise of a patent. However, as stated in the passage quoted from Duff C.J. of the Supreme Court in Western Electric, who in turn quoted Lord Buckmaster in British Thomson-Houston, construction of the specification (which is where the promise is set out) is within the exclusive province of the Court. Expert evidence may and often must be received in interpreting terms of art and providing the Court with the state of the art background within which the specification is to be considered.

Hughes J’s view respects the proper role of expert witness and legal advocates, it avoids the need to disguise legal argument as evidence, and it is certainly supported by ample authority.

The leading authority for the contrary view, that the task of the court is solely to the determine what the posita would have understood the language to mean, is Catnic, [1982] RPC 183 at 243 (HL) in which Lord Diplock stated that the “purely literal” interpretation of the Court of Appeal, “derived from applying to it the kind of meticulous verbal analysis in which lawyers are too often tempted by their training to indulge.” This is not a compelling argument in favour of treating interpretation of the patent as a matter solely for expert evidence. The Catnic problem can be addressed with the well-established maxim that the patent is to be read by a mind willing to understand. Even a lawyer’s mind, if willing to understand, will appreciate that the meaning of a term like “vertical” varies with the context and does not always mean precisely 90 degrees. The purposive interpretation established in Catnic does not reflect a difference between legal minds and technical minds, which implies that a patent can only be truly understood by a scientist or engineer. Rather, it is a reflection of the general principle that any legal document must be read purposively. This undoubtedly applies, for example, to the interpretation of statutes, where expert evidence is rare, and it is uncontroversial that legal argument appropriate. A patent is a regulation under the Interpretation Act (and see Whirlpool 2000 SCC 67 [49]) and legal argument is just as appropriate in the construction of a patent as it is in the construction of a regulation.

No comments:

Post a Comment