Friday, July 8, 2016

A Teaching Example on Claim Construction

Bristol-Myers Squibb v Teva 2016 FC 580 Mactavish J
            2,250,840 / 2,317,736 / atazanavir / REYATAZ

My previous post gave an overview of the facts of this decision and discussed some of the issues related to obviousness. This post discusses a tricky claim construction issue that arose in the context of the 736 patent. While it did not raise any new legal issues, it is a good example of the tension between the primacy of the claims and the principle that purposive construction requires that the claims are read in the context of the specification as a whole.

Loosely speaking, the 736 patent claimed atazanavir bisulphate. There are two known forms of atazanavir bisulphate: Type-I is anhydrous whereas Type-II hydrated [271]. Type-II is apparently unsuitable for use in oral dosage form, and accordingly the patentee argued that the claim encompassed only Type-I, while Teva argued that it covered both types [275-76].

More specifically, Claim 1 was:

1.         The bisulfate salt having the formula

It was common ground between the experts that the structural formula for a hydrated crystal such as Type-II bisulfate crystals would include a term “•H2O” to the right of the “•H2SO4” on the right side of the diagram in Claim 1 [365]. As the “•H2O” was absent, Mactavish J concluded that the structural formula in Claim 1 encompasses only Type-I salts, and “clearly” does not include Type-II hydrated salts [365], [369], [373].

Teva’s strongest argument for the contrary interpretation was based on Example 3 of the disclosure. This was set out in the section of the disclosure with the general heading “Description of Specific Embodiments,” indicating that all the subsequent examples, including Example 3, were embodiments of the invention. Example 3 itself, “Preparation of Bisulfate Salt from Isopropanol,” acknowledged that the crystals produced by the process it described were Type-II crystals of a “hydrated, hygroscopic crystalline form” [315]. Moreover, the disclosure at p7 introduced the examples by saying “[t]he bisulfate salt may be prepared,” by using “solvents such as . . .isopropanol.” The term “bisulfate salt” is the same as that used in Claim 1. Teva argued that in effect the patentee was constructing its own dictionary in the disclosure, telling the reader that the ‘the bisulfate salt” included all the embodiments set out in the examples, which included the Type-II form [316].

Thus, the claim on its face clearly says one thing – only Type I salts are included – but the disclosure clearly says another thing – both Type-I and Type-II salts are included.

Two basic principles led Mactavish J to the conclusion that the claim was properly construed as including only Type-I crystals. One is “the primacy of the claims language” [345] (quoting Free World Trust 2000 SCC 66, [30]). As Mactavish J put it, “[w]hile the specification does describe the invention, the scope of the monopoly is defined by the claims” [345]. I would add that the SCC in Free World noted that the disclosure cannot be used to rescue poorly drafted claims: “ if the inventor has misspoken or otherwise created an unnecessary or troublesome limitation in the claims, it is a self-inflicted wound” [51]. But presumably the converse is also true: if the claims have avoided an unnecessary or troublesome limitation, then the disclosure should not be used to undermine the claim language. The second principle invoked by Mactavish J is that claim construction should “endeavour to support a truly meritorious invention” [283], [342] (and see Consolboard [1981] 1 SCR 504, 520-21).

The counter-argument, of course, is that “the Court may, where necessary, have resort to the disclosure” to assist in claim construction [347]. However,

[348] While one can look to the specification where the claims of a patent are not clear, there is a clear limitation on the use that can be properly made of it. It is not permissible to read the specification in order to construe the claims more narrowly or widely than the text will allow.

The FCA in Dableh [1996] 3 FC 751 summarized the law this way:

recourse to the disclosure portion of the specification is: (1) permissible to assist in understanding the terms used in the claims; (2) unnecessary where the words are plain and unambiguous; and (3) improper to vary the scope or ambit of the claims.

In Catnic [1982] RPC 183 (HL), for example, the crucial word in the claim was “vertically,” and the HL held that in light of the purpose of the vertical support as described in the disclosure, this should be interpreted to mean near enough to vertical to enable the back plate to perform its function. But if the claim had instead said “90 degrees, plus or minus 1 degree,” it would not include a plate at 87 degrees, even if that was functionally vertical.

I have argued that it is always necessary to look to the disclosure, as the disclosure may reveal that a term that is apparently clear is in fact ambiguous. But even if that is so, it would not make any difference in this case, as the disclosure did not reveal a latent ambiguity in the claim, it revealed a conflict between the two. In that case, the claims have priority.

Given Mactavish J’s finding that claim in its own terms clearly encompassed only Type-I crystals, the principle that the disclosure cannot be used to vary the ambit of the claims leads directly to the conclusion that the claim should be construed as covering only Type-I crystals. There was no real need to rely on the woollier maximum that the patent should be approached “with a judicial anxiety to support a really useful invention” (Consolboard 521), which was merely supplementary.

What makes the problem trickier, at least for me, is that I am not entirely persuaded that the claim itself was so clear on its face that hydrated salts were excluded. I acknowledge that I do not have the advantage of the full record, so I am not really in a position to disagree with Mactavish J’s finding. But consider this hypothetical. Suppose that the inventor had never tried the isopropanol process, which was the only one of the four processes set out in the examples which produced the Type-II crystal, and so did not realize that there was a hydrated form. The patentee would presumably have drafted exactly the same Claim 1. Suppose also that there was no particular ingenuity involved in the isopropanol process (as seems to be the case); there were many solvents that could have been used and it just happened that the ones the patentee had tried produced Type-I crystals. Subsequently, the generic seeking to attack the patent had tried isopropanol and had discovered that it produced the Type-II hydrated crystal. How should Claim 1 be construed? It seems clear that Mactavish J would hold that only Type-I crystals were covered, as the absence of Example 3 would strengthen this conclusion in this hypothetical as compared with the actual facts of the case.

But now change the hypothetical slightly. Suppose, counter-factually, that the Type-II crystal turned out to be perfectly suitable for use in oral dosage form, so that if the Claim 1 was construed to exclude Type-II crystals, the generic would have been able to compete effectively without infringing. Now how should the claim be construed? The specification is exactly the same as in the previous hypothetical, with the same Claim 1 and no Example 3. That implies that only Type-I salts are included. Would that be considered a “self-inflicted wound,” even though the patentee was not aware of the Type-II salts in drafting the specification?

But something has changed. On the actual facts of the case and in my first hypothetical, the inventor’s true contribution was that Type-I atazanavir bisulfate salts were suitable for oral administration. In my second hypothetical, the inventor’s true contribution would be that all atazanavir bisulfate salts were suitable for oral administration. In the second case the principle that claim construction should “endeavour to support a truly meritorious invention” would imply that the claim should be construed to include both types of crystal. I wouldn’t be at all surprised if, on the facts of my second scenario, a court found Claim 1 to include both salts. But such a claim construction would require the principle that claim construction should “endeavour to support a truly meritorious invention” do to real work.

I would also suggest that what is important here is the objective nature of the invention, and not the inventor’s subjective state of mind. In my hypothetical the inventor did not fully realize its true contribution, as it was not aware of the Type-II crystals. It is plausible that the inventor on the actual facts did not recognize its true contribution either; while Mactavish J did not make a finding one way or the other, it may be that the inventor did not realize that Type-II salts were not suitable. That might seem to give rise to a tension with the principle that the claims are to be read according to the intent of the inventor; but that intent is determined objectively, from the patent itself, and not from evidence as to the inventor’s state of mind: Free World Trust 2000 SCC 66, [66].


  1. We all live in the same imperfect world. Nobody has universal knowledge of everything, neither an inventor nor his/her patent agent. So they make their best with what they have at the time, and have to live up with the outcomes. But justice finds its purpose in that. And so far, I believe that common sense still prevails. It sometimes involves warping the case law so that a patent for a meritous invention stands against all odds, despite possible causes for a better wording.

  2. its really unfortunate but patent agents are paid to prevent these types of mistakes. so too bad, blame the P.A.