Lessons for patent applicants and patent agents

While the Aug. 12 decision of the Federal Court of Canada in Ratiopharm Inc. v. Pfizer Ltd. will almost inevitably be appealed, it provides an unusual insight into the nuts and bolts of the process of developing an invention and drafting a patent application.


The judgment was written by Justice Roger Hughes, who was a leading IP lawyer, and it provides valuable guidance for patent agents and their clients.

While the Canadian patent in issue, CA1,321,393, arose from an application filed in 1987, under an earlier version of the Patent Act (commonly referred to as the old act to distinguish it from the current, new act), much of the statutory language analyzed is essentially unchanged and the court’s conclusions are directly relevant to current applications.

The most basic requirements for patentability are that an invention must be novel (it must be new compared to the prior art), must not be obvious (it must be inventive compared to the prior art) and must have utility (it must work). The application of these and other criteria for a valid patent have naturally been fleshed out in considerable detail in the relevant court decisions.

In this case Ratiopharm Inc. challenged the patent on grounds of obviousness, insufficiency of the specification, lack of utility, failure to present a valid selection, and misrepresentation under s. 53(1) of the Patent Act, which is essentially unchanged between the old and new acts. A challenge for lack of novelty was dropped by agreement between the parties, and to simplify matters the parties agreed the case would be decided based on the wording of a single claim, claim 11, which recites “[t]he besylate salt of amlodipine.”

The Patent was held invalid on all of the grounds argued. The Court summarised the facts as follows:
“Pfizer developed its amlodipine drug through a routine pre-formulation procedure in which a common procedure called a salt screen was conducted. As a result of that salt screen, of the seven or so salts tested besylate was selected as the preferred salt. It was not clearly superior to three or four others tested particularly those of the sulphonate group (besylate, mesylate, napsylate, tosylate) but was chosen as a reasonable compromise. Some executives made a decision to seek patent protection. The inventors recommended the besylate, tosylate and, possibly the mesylate for that purpose. The patent department singled out the besylate only, mixed data from some tests with data from other tests, put in data that cannot be found anywhere in evidence and left out data favourable to other salts while using words such as unique and outstanding and particularly suitable when referring to the besylate-words the inventors never used.”

The judgment analyses the language of s. 34(1) of the old act (now contained in s. 27(3)) namely that: “[t]he specification of an invention must . . . correctly and fully describe the invention and its operation or use as contemplated by the inventor” [emphasis added].

The court emphasized the importance of analyzing the invention “as claimed,” and declined to merely assume that what the disclosure said was what the inventors had actually contemplated.

While the inventors had proposed an application to encompass both besylate and tosylate salts of amlodipine, the final application focused only on the besylate salt and used various superlatives to describe the besylate salt and to distinguish it from other possible salts of amlodipine.

This was combined with inaccurate and misleading experimental data. It was therefore held that in view of the various errors, omissions, insertions, and departures between what the inventors had contemplated and what patent disclosed, the invention had not been “correctly and fully” described “as contemplated” by the inventors. Consequently, the disclosure was incomplete and the patent was invalid for insufficiency of the disclosure.

In considering an allegation that the patent was invalid under s. 53(1) (the wording of the section is the same in both the old and new acts), because of misleading statements in the specification, the court compared what the specification promised to what the claimed invention actually delivered.

While the specification used superlatives to characterize the besylate salt, the besylate did not possess the alleged advantages over other candidate salts that had been tested. While the specification indicated that the solubility of certain salts had been tested, the evidence suggested that these had in fact not been tested at all.

Some stability data presented was wrong and the court found the hygroscopicity data “careless and incomplete.”
The superlatives used in the disclosure emphasized the misleading effect of the questionable experimental data presented and were not supported by the evidence.

Since these misleading statements and omissions appeared in the specification not by accident, but as a result of conscious decisions on the part of one or more individuals, the court held that the patent was invalid under s. 53(1) because the specification contained “more or less than [was] necessary . . . and the omission or addition [was] wilfully made for the purpose of misleading.”

In Canada, the courts have historically been very reluctant to declare patents invalid for misrepresentation and omission by the patentee. This is not, however, the only judgment in recent years to try and impose an increased duty on applicants to provide a full and fair disclosure of relevant facts in exchange for the exclusive right and privilege that is granted in an issued patent. Take the 2007 ruling in Pason Systems Corp. v. Canada (Commissioner of Patents), for example.

The court insisted that allegations of this nature must be specifically pleaded and not merely implied from other language in the pleadings.

In similar reasoning to that used in connection with ss. 53(1) and 34(1), the court also held the patent to be invalid for lack of utility because it did not deliver on its promise of a unique and outstanding invention.

The judgment’s discussion of when an invention is “obvious,” and therefore not patentable, and the related issue of what constitutes a valid selection patent — this can be seen as a particular subset of the obviousness inquiry, where a compound is selected from an among known group because it displays special advantages compared to other members of the group — is also helpful.

The salt-testing procedure adopted was an obvious and routine approach to the problem faced, namely identifying a salt suitable to make the desired dosage forms. In its search for a suitable salt of amlodipine, the applicant tested only a handful of salts, all selected because they were already accepted in the art as species which generally had suitable pharmaceutically acceptable properties.

Among the handful of candidate salts tested, the researchers recommended that several be pursued but ultimately the application focused only on the besylate salt. Since neither the candidate salts nor the method adopted to identify them were found to be inventive, and since there was therefore no meaningful trial and error to identify the besylate salt, the court held that it was not inventive. Therefore the patent was invalid because the claimed invention was obvious.

Because the besylate salt did not have special advantages over a prior art disclosure that listed besylate amongst a series of other possible salt forms, it was also not a patentable selection.

While their importance and application is going to vary with the circumstances of each individual situation, the case has several messages for applicants and agents:

•    a patent application should not be used as an advertising document. The applicant may be held to superlatives and puffery and the patent declared invalid for failing to deliver what it promises;

•    members of a class should not be arbitrarily singled out for emphasis over others, and substantive advantages of a particular choice should not be alleged, unless there is real support for them;

•    experimental examples presented should be real and any data presented should accurately reflect the experiments that were done. There are risks involved in selectively omitting data that may be relevant to an understanding of the invention as it was contemplated by the inventor;

•    while the decision to file an application is clearly a commercial decision as much as a scientific or legal one, once that decision is made, there should be limits on the “business” input into the wording of the application. It is probably safer to leave the drafting process to the inventors and the patent agent; and

•    the court’s analysis of what is “obvious” in terms of testing of salts of a known compound may be significant in various contexts. A similar approach would seem easily applied in considering when, for example, the process of selecting variants of an organic compound or selecting the sequence of a DNA probe for particular purposes may be “obvious” and the resulting choice may be unpatentable.

While one may not wish to see a Canadian regime quite so oppressive as that in the United States, it is to be applauded that the courts are showing themselves more inclined to impose sanctions on patentees who intentionally mislead the Patent Office and the public.

Dr. Euan Taylor is the head of Davis LLP’s patent practice group and is a registered Canadian Patent Agent and qualified arbitrator. His e-mail is etaylor@davis.ca. The author thanks Kevin Wright, also of Davis, for his comments and ideas.

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