Is Minerals Separation Still Good Law?

Leo Pharma Inc v Teva Canada Ltd 2015 FC 1237 Locke J
            2,370,565 / calcipotriol & betamethasone / DOVOBET

In this NOC proceeding Locke J granted an order of prohibition as infringement of multiple claims was conceded, and he held that Teva’s allegations of obviousness, lack of utility and insufficiency were not justified [193]. The holding turned on the facts of the case, but the claim construction argument raises the question of the continued vitality of Minerals Separation.

The claimed invention is a dermal cream formulation for the treatment of psoriasis. Vitamin D and vitamin D analogues, specifically calcipotriol, were previously known for treatment of psoriasis, as were corticosteroids (such as betamethasone), and these were commonly used sequentially. There was consequently a motivation to develop a combined formulation, but the two drugs could not simply be mixed because they were pH incompatible, which is to say that calcipotriol was unstable at any pH value which was favourable to the stability of a corticosteroid, and vice versa [54], [55], [108]. Leo discovered a stable formulation containing these compounds plus the solvent POP-15. Claim 1 was to a formulation comprising vitamin D or a vitamin D analogue (component A), a corticosteroid (component B) and a solvent selected from a large class, while Claim 17 specified POP-15 as the solvent. (Claim 17 was the only claim held to be useful and infringed. The utility of the other infringed claims was not addressed.)

The patent itself disclosed that a formulation using propylene glycol as a solvent was unstable [19]. Teva argued that because the wording of the claims is non-exhaustive (using "comprising") and there is nothing in the claims to suggest that they are limited to compositions that are useful in treating psoriasis, the claim should therefore be construed as encompassing formulations with an additional  component, such as propylene glycol, which would not be useful [89]. More generally, if Teva’s argument were sound, any claim using “comprising” language would be invalid unless it was expressly limited to safe or effective formulations, as a claim not so limited would encompass the formulation plus Compound X, where Compound X is a poison.

Functional Limitations Need Not Be Express in the Claim

Delp v Fresh Headies Internet Sales Ltd 2011 FC 1228 Barnes J

This decision is a reasonably straightforward application of Burton Parsons [1976] 1 SCR 555 in the context of a motion for summary judgment. The claimed invention is for a method of extracting resins from plant materials without the use of chemicals, by chilling the plant material in cold water, which causes the resin to become brittle, and then agitating, which causes the brittle resin to break off the plant surface, after which it can be removed by filtration.

The problem faced by the patentee was a familiar one. The process can be made to work over a range of temperatures, though the efficacy drops off gradually at increasing temperatures. If the temperature is too high it will not work, though there is no strict cutoff point. Further, it will work for a variety of resinous plants, and the temperature at which the process becomes inoperative depends on the plant. A low temperature cutoff in the claim would risk excluding practically operable embodiments of the invention that could be used by competitors, but a cutoff that is too high risks encompassing inoperable embodiments.

Claim Construction and Inoperable Species

Merck & Co Inc. v. Apotex Inc. / lovastatin 2010 FC 1265, Snider J

As noted in my last post, claim 1 of the patent at issue in the lovastatin case related to a specified compound produced by the microorganism A. terreus. It was established [492] that not all stains of A terreus would produce the product in question. Apotex argued that the claim was therefore invalid for lack of utility [492]. Snider J rejected this argument on the basis that the claims, properly construed, included only those strains capable of producing lovastatin [494], [110]-[121].

This point of claim construction is important because of the rule that a claim lacks utility if “[t]ere is evidence of lack of utility in respect of some of the area covered” [495]. I argued in a previous post that this rule is unsound. However, it has been accepted and applied in two SCC decisions, namely Minerals Separation North American Corp. v. Noranda Mines Ltd. (1952) 69 R.P.C. 81 (J.C.P.C.) affm’g [1950] S.C.R. 36(SCC) and Société des Usines Chimiques Rhone-Poulenc v. Jules R. Gilbert Ltd [1968] S.C.R. 950. Consequently, rather than rejecting the rule itself, Canadian courts have largely avoided its application by construing the claims to exclude the inoperable species, as did Snider J. This approach was established by the SCC decision in Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd. [1976] 1 S.C.R. 555 which distinguished Minerals Separation and Rhone-Poulenc on the basis of claim construction.

In Burton Parsons, the claim in question, to an electrocardiograph cream, specified that a cream of specified composition that was “compatible with normal skin.” The SCC adverted to this, noting that in  Minerals Separation and Rhone-Poulenc “the object of the patent was some substances of a definite chemical composition” and “[u]nfortunately for the patentees, the claims covered at the same time” some compounds which were not useful for the specified purposes. The Court also noted that the inutility of the compounds in the earlier cases “was not known to the prior art. This is totally unlike the undesirable properties of some highly ionizable salts which Hewlett-Packard listed as objectionable. Their noxious character was well known . . .”

Thus Burton Parsons left two points open. First, what are the limits of such functional phrases: is it necessary that the inoperable embodiments were known at the time? Second, is it necessary that the claim expressly state a functional limitation, such as “compatible with normal skill,” or can this be read in on the basis that a person skilled in the art would appreciate that requirement? There was certainly many statements in Burton Parsons that would imply a generous reliance on the understanding of a person skilled in the art, but the points on which the Court distinguished the prior cases suggest a narrower approach.

The first question was addressed in Apotex Inc v Lundbeck Canada Inc / escitalopram (NOC) 2010 FCA 320 (Noël JA: Pelletier, JJA) affm'g 2009 FC 146 (Harrington J), in which claim 1 claimed “non-toxic acid addition salts” of the specified compound. The  pamoic acid salt was conceded to be toxic [105], and Apotex argued that claim 1 was therefore invalid, as there was no suggestion that pamoate salt was toxic as of the claim date. It appears to be very clear on the facts that the toxicity of the pamoate salt would not have been obvious on the claim, as the patentee has specifically claimed that salt in claim 2, which was held to be invalid for that reason. The FCA nonetheless held that claim to be valid as excluding non-toxic salts in its terms, including the pamoate acid salt [108]. It appears, therefore, that it is not essential that the functional limitation be known as of the claim date.

The second question was at issue in the lovastatin decision as “[n]either claim 1 nor the specification explicitly states that the '380 Patent excludes nonproducing strains of Aspergillus terreus” [111]. It was established on the facts that a skilled person would know that not every strain of A terreus would produce the desired results [117] and that it would be routine for a skilled person to identify and optimize the producing strains [120]. On these facts, Snider J had no difficulty finding that it was an implicit requirement that non-producing strains are excluded from the scope of the claim [121]. In support of this conclusion, she cited only the general principle from Consolboard [1981] 1 SCR 504, 520, that the patent should be read “being neither benevolent nor harsh but rather seeking a construction which is reasonable and fair to both patentee and public.” While Snider J’s decision was not unduly burdened with authorities on this point (it should be understood that this was a relatively minor part of a long and complex decision), general principles are enough to show that her holding is surely right: a patent must be approached with  “a mind willing to understand, not by a mind desirous of misunderstanding” (Whirlpool v Camco 2000 SCC 67 [49(c)]). If more authorities are needed, we may note that her holding is consistent with the dictum in Burton Parsons that “In Sandoz Patents Ltd. v. Gilcross Ltd., we had no hesitation in upholding claims for "therapeutically tolerable salts" of thioridazine to be obtained by reacting "with a therapeutically acceptable acid". I cannot think that the omission of the qualification "therapeutically acceptable" would have voided the patent and I will note that in the Rhône-Poulenc case this question was left open.”

But if Snider J is right that the operability limitation can be implied, and the FCA was right in Lundbeck / escitalopram (NOC) that inoperability need not be known as of the claim date, then it becomes increasingly difficult to distinguish Minerals Separation and Rhone-Poulenc. I argued in my last post that the principle they stand for is unsound. It now seems evident that they would not be decided the same way today. Perhaps the time has come to recognize that they are no longer good law.

Utility and Inoperable Species

Merck & Co Inc. v. Apotex Inc. / lovastatin 2010 FC 1265, Snider J

Claim 1 of the patent at issue in the lovastatin case (#1,161,380) related to a specified compound produced by the microorganism A. terreus. It was established [492] that not all stains of A terreus would produce the product in question. Apotex argued that the claim was therefore invalid for lack of utility [492]. Snider J rejected this argument on the basis that the claims, properly construed, included only those strains capable of producing lovastatin [494], [110]-[121].

This raises two questions. The most obvious is as to whether Snider J’s construction of the claim was sound, particularly because neither claim 1 nor the specification explicitly states that the '380 Patent excludes non-producing strains of A. terreus [111]. In other words, is it permissible to read in an operability limitation?

The more fundamental question concerns the underlying rule of law respecting utility. It is now routine in Canadian law to say that a claim lacks utility if “[t]here is evidence of lack of utility in respect of some of the area covered” by the claim [495], quoting Wellcome / AZT 2002 SCC 77 [56]. This rule can operate harshly. If an inventor discovers a new class of compounds that are generally useful, for example in treating a deadly disease, this rule implies that even if a single compound within that class does not have the promised utility, the claim is invalid, even though a person skilled in the art would have no difficulty identifying the inoperative species. This consequence may be avoided if the claims are construed to exclude inoperable species, as in Snider J’s lovastatin decision, but the claim construction issue cannot be properly understood without casting a critical eye on the underlying utility doctrine.