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.

The solution to the problem is also familiar. So long as operable range for any particular plant can be ascertained by a skilled person without undue effort, the claim can be framed in functional terms. This is the key point of Burton Parsons. The problem then becomes one of construction. On the most conservative reading of the case law, if the patentee’s claim clearly encompasses inoperable embodiments, the claim will be invalid even if it would be obvious to a skilled person to avoid such embodiments: see Henriksen v Tallon Ltd (1965) RPC 434 HL quoted by Barnes J at [17]. (I have argued elsewhere that this doctrine is unsound, but the issue does not arise in this case.) But if the claim, properly construed, encompasses only operable embodiments, and determining which embodiments are operable does not require undue effort, the claim is valid.

The claim at issue specified steps including “(a) placing a quantity of water having a temperature in the range of 0°C to 15°C into a washing chamber” and “(c) adding a quantity of ice to the quantity of plant material and water in the washing chamber.” The plaintiff’s evidence indicated that the process would not work at 14-15 °C for at least some plants, such as cannabis [20] (it appears that the main application of this process is in making hashish from cannabis). The defendant argued that the claim was therefore invalid.

Barnes J rejected this argument. As a matter of law he affirmed that Burton Parsons “did not turn solely on the language of the impugned claim which included a reference to the product being compatible with normal skin” [16]. It is not necessary to have magic words in the claim that expressly state that the claims are confined to operable embodiments, so long as this is clear from the specification as a whole. As Barnes J noted, this was evident from Burton Parsons itself, but it is nonetheless useful to have express clarification. Barnes J’s holding on this point is consistent with the decision of Snider J in Merck & Co Inc. v. Apotex Inc. / lovastatin 2010 FC 1265 (discussed here), and we can now take this point to be established in Canadian law.

On the specific claim, Barnes J held that the defendant’s argument was wrongly premised on the view that “the temperatures that the Plaintiff was referring to for maximizing utility were those of the water bath after the addition of ice and not the range of temperatures stipulated at the beginning of the process” [23]. That is, the process would work, even for cannabis, with a starting temperature of 15°C once the temperature was subsequently lowered into the optimal range by the addition of ice as specified in step (c). An interesting question would arise if the defendant started with a temperature that was far outside the range specified in step (a), such as warm water at 25°C and then chilled the mixture to the operable range as specified by step (c). Barnes J’s stated that “it is not necessarily the beginning temperature of the water that is essential but rather the optimal operating temperature which is achieved by the addition of ice to the water bath. It is through the addition of ice that the water temperature drops to a point that the resin becomes brittle and can be separated” [12]. This suggests that even a starting temperature well above the range specified in step (a) might infringe, on the basis that the starting temperature is not an essential element of the claim. Of course, the essential elements doctrine is uncertain and rarely used, and this question did not arise in this motion for summary judgment, which addressed only invalidity based on lack of utility.