Wednesday, November 14, 2012

What Is the “Invention”?

Teva Canada Ltd v Pfizer Canada Inc2012 SCC 60 LeBel J for a unanimous court,* rev’g 2010 FCA 242 Nadon JA: Blais CJ, Trudel JA rev’g 2009 FC 638 Kelen J
            2,163,446 VIAGRA

As I noted in yesterday’s post, the Pfizer / sildenafil decision was fundamentally about the patentee’s duty to disclose the invention. But what is “the invention”? Sildenafil had not been explicitly identified in the description as compound which had been tested and found to work, but it had been separately claimed in Claim 7. The ultimate question was whether the identify of sildenafil as the tested compound was sufficiently disclosed. The doctrinal argument turned on whether each claim is to be considered a separate invention [53ff]. At trial, Kelen J had felt bound by the prior case law to hold that each claim defines a separate invention [FC 44, 148], and this was affirmed by the FCA [FCA 65].** This conclusion effectively determined the outcome. As the FCA explained at [71]:

The appellant argues that the Judge was not entitled to find that the patent was clear because Claim 7 was clear. However, the Judge was never actually required to find that the '446 Patent itself was clear. Rather, he was required to find that the '446 Patent clearly revealed the invention disclosed by Claim 7.

That is, once we have decided that the invention is sildenafil (more precisely, the use of sildenafil to treat ED), it follows that the invention was sufficiently identified, since the claim itself explicitly identifies sildenafil. The SCC reversed on the basis that in this case, the specification as a whole must be considered [64], and “there is only one invention: the use of the compound or compounds that are effective in treating ED” [68]. That being the case, it does not follow directly that the invention was sufficiently identified, because the question is whether Claim 7 (which is part of the specification), in conjunction with the disclosure, sufficiently identifies the tested compound. This will depend on the particular patent.

Note that the SCC did not hold that there is always only one invention. On the contrary, it held that “It is possible, as in Boehringer, for each claim in a patent to disclose a separate invention” [64]. However, the SCC did not provide any clear test for deciding when each claim defines a separate invention: “Where this issue is raised, however, individual patents must be considered on a case-by-case basis” [64]. The Court implied that whether each claim defines an invention turns on the construction of the specification [67].

While I agree with the Court’s conclusion in this case that it was appropriate to look to the specification as a whole, I am not comfortable with the suggestion that whether that is appropriate depends on the construction of the specification. This implies that in any similar case, we must first construe the disclosure to determine whether each claim is a separate invention, before deciding whether the invention is sufficiently disclosed. This is likely to generate uncertainty.

The problem arises because there are two principles which point in different directions as to the meaning of “invention.” One, emphasized by the SCC at [58], is the requirement of unity of invention set out in s 36(1): “A patent shall be granted for one invention only.” The other is the rule that claims stand or fall independently, set out in s 58.

How should these rules be reconciled? One approach is to say that there is no conflict, as s 58 does not refer to the “invention” but only to “claims.” So the SCC stated at [56] that

Section 58 simply states that valid claims survive in the face of one or more invalid claims. This section is engaged once it has been determined, on the basis of the patent as a whole, whether the requirements, including the disclosure requirements, have been complied with. . . . This section is engaged only after the validity analysis is carried out.

However, this statement is problematic. Section 58 has traditionally been understood as requiring not only that claims stand or fall independently, but also that validity must be assessed in respect of each claim independently. How can claims stand or fall independently if s 58 is engaged “only after the validity analysis is carried out”? If validity is assessed on the basis of the patent as a whole, then the claims must stand or fall together. Moreover, to the extent that the SCC is suggesting that obviousness and novelty are to be assessed on the basis of the specification as a whole, and not on the basis of the particular claims, this is inconsistent with s 28.2 and 28.3 of the Patent Act, which define the novelty and non-obviousness requirements in terms of “the subject-matter defined by the a claim.”

Rather than dividing validity and the application of s 58, as the SCC has done, I suggest that a better approach is to separate the disclosure requirement, which was at issue in Pfizer / sildenafil, from obviousness, utility and novelty. In so doing, it is helpful to distinguish two senses of “invention,” which may be used to mean the “inventive concept” or “the invention as disclosed,” and, alternatively, it may be used to mean “the invention as claimed.” Sufficiency of disclosure is directed to the inventive concept, and so the specification as a whole, while novelty etc are directed to the invention as claimed. The two are linked because the inventive concept is the inventive concept underpinning the claims, even though the sufficiency of the disclosure is interpreted in light of the specification as a whole.

This distinction is consistent with the Act, as least to the extent that s 28.2 (novelty) and 28.3 (obviousness) refer to “the subject-matter defined by the a claim” – which is clearly the invention as claimed – while s 27(3) (disclosure) refers to “the invention” – which is arguably the invention as disclosed, or the inventive concept. (Of course, “useful” appears only in the definition of “invention” in s 2, so it does not fit neatly into this dichotomy.) Conceptually, sufficiency of disclosure is necessarily a property of the specification as a whole. Consider a patent for a Compound X that has been disclosed to be a cure for cancer. The claim itself will claim the compound per se. It is not possible to assess the sufficiency of the disclosure, whether in the most basic sense of whether a method of making Compound X has been disclosed, or in the sense of whether the use of Compound X as a cure for cancer has been disclosed, without looking to the disclosure. On the other hand, novelty, non-obviousness and utility may be assessed without reference to the disclosure, and often this is necessary. Obviousness, for example, is determined objectively. The inventor may think that she has come up with an invention of genius, but if she was unaware of a crucial part of the prior art, she may be quite wrong. Or she might be wrong as to the nature of the inventive contribution; she may believe that she has discovered an entire new genus, but in fact only a single species from that genus was novel. For that reason, it is the invention as claimed, not the invention as disclosed, which must be novel, non-obvious and useful.

The requirement of unity of invention, relied on by the SCC, like the requirement of disclosure which was at issue, is directed to the inventive concept. The rationale is that the examination burden on the Patent Office increases substantially with each new inventive concept, and the fees charged are appropriate for considering only one inventive concept. (Note that in 19th century English patent practice, patents claiming entirely distinct inventions were quite common, precisely in order to save on examination fees.)

Leaving aside cases in which a patent improperly contains two distinct inventive concepts, if there is only one inventive concept in a patent, why are there separate claims? As a practical matter, there are two main reasons for separate claims. One is that different claims may capture different embodiments of a single inventive concept. If the inventive concept is the discovery that drug X cures cancer, the drug itself will be claimed, as well as the drug in the salt form, the drug in table form with excipients etc. In principle, a single claim to the drug itself would be adequate, as the other forms would infringe even if not specified, just as in claiming the drug as a pharmaceutically acceptable salt it is not necessary to specify each such salt individually. Here, multiple claims are used to simplify the infringement analysis. Even though only one claim may be at issue in litigation, in such cases all the claims will normally stand or fall together, and there is no conflict between the requirement of unity of invention and the rule that claims stand and fall independently.

Alternatively, multiple claims may be used to address validity issues. For example, when a patentee claims a genus, then a selection from that genus, and so on down to an individual compound, as in Pfizer / sildenafil, this is to retain some valid claims in case the broader claims are invalid. A conceptual difficulty arises because the inventor may be mistaken about the inventive concept. For example, the inventor may believe she has discovered a new genus that is useful for curing cancer, but she may be wrong. Some members of the genus may not be useful, or may be already known. In this case, the requirement of unity of invention is satisfied during examination because there is apparently a single inventive concept, in the view of both the applicant and the examiner. With the extra information available in litigation, it turns out that the single inventive concept that unifies all the claims, and that was the focus of the disclosure and examination, is not the true inventive concept at all; the true inventive concept is the narrower concept underpinning a specific claim (or subset of claims). That is, the apparent inventive concept may have been that genus X cures cancer, but the true inventive concept was that species Y cures cancer. In this context, it would be wrong to assess validity, including sufficiency of disclosure, on the basis of the single inventive concept that underpins all the claims. For example, suppose that some of the members of the genus were particularly difficult to make, and the specification did not sufficiently disclose how to do so, even though it disclosed clearly how to make species Y. The claim to species Y will not be invalid for failure to disclose how to make genus X. However, this does not mean that sufficiency is a property of the claim. It remains true that the disclosure of how to make species Y and the fact that it is a cure for cancer, is found in the specification as a whole; these disclosures are in the description, not in the claims. Sufficiency of disclosure must still be assessed on the basis of the disclosure as a whole, but it must be assessed in light of the invention as claimed.

On this logic, even though sildenafil was claimed in Claim 7, the inventive concept of Claim 7, which was the use of sildenafil as a treatment for ED [65], was not sufficiently disclosed because the specification as a whole did not identify sildenafil as the compound that had been tested. We cannot assume that sildenafil must have been tested simply because it was separately claimed; there were in fact two claims to individual compounds, and there might in principle have been many, notwithstanding that only one had been tested. 

While this argument has gotten a bit convoluted, I suggest that the basic point is intuitive. Disclosure is a property of the specification as a whole; novelty, utility and obviousness are properties of the invention as claimed. That disclosure is a property of the specification is clearly true in respect of the classic requirement of how to make the compound, for example, but it is also true of the more general obligation at issue in Pfizer / sildenafil, of disclosing the “invention” which is to say disclosing the inventive concept. I acknowledge that this approach which distinguishes the disclosure requirement from other validity requirements, is inconsistent with the statement by the SCC in [58] which includes the disclosure requirement along with other requirements. But I submit that this approach is consistent with the Pfizer / sildenafil decision as a whole, which is focused on the disclosure requirement. Paragraph 58 began with the statement that “Pfizer is suggesting that under s. 58, where a valid claim exists, the consideration of the disclosure requirements can be limited to that claim,” and it is really this proposition that is being rejected. Moreover, the distinction between disclosure and other requirements is consistent with the Act.

*McLachlin C.J. and LeBel, Deschamps, Abella, Rothstein, Cromwell and Moldaver JJ.

**More precisely, the FCA held that “where a single patent application separately claims a class of chemical compounds and a single compound within that class, each separate claim discloses a separate invention” [FCA 31, quoting Merck vApotex / lisinopril, 2006 FCA 323 [31]]. While the FCA emphasized this point, it is not clear how and on what principle this is different from saying that each claim is a separate invention.

1 comment:

  1. Thanks for the excellent analysis. I think there is an underlying issue that adds to the confusion that you partly touched on. I think you have to interpret the single invention requirement to mean that the claims must share (what the inventor believes to be) a single inventive concept. However, dependent claims can claim “sub-inventions” that are patentably distinct from their parents. A key application of s. 58 (in combination with the fact that a patent is not invalid if it does claim more than one invention) is that if the broad inventive concept is later found to be in the prior art, so knocking out the independent claims, multiple patentably distinct dependent claims to multiple inventions can stand separately. The disclosure requirements for each of the sub-inventions are not clear, given the SCC’s statement at [56], but it seems each patentably distinct set of claims should be subject to a separate validity analysis, including proper disclosure, after the broad claims are knocked out. After all if the examiner had knocked the broad claims out, and the distinct remaining claims were packaged in divisionals, this would be the case. Otherwise the patentee would be better off because of the examiner's failure to find relevant prior art.

    By the way, dependent claims can also be useful for claim differentiation purposes, and to make it clear that certain embodiments are definitely intended to be within the parent claim scope. In prosecution, they can also be useful to try to make the examiner directly address certain limitations.