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Crisp boundaries: Federal Court defines the scope of protection for French fry manufacturing process patent

Authored byMatthew Norton, Emily Miller, Jean-Sébastien Dupont and Daniel Davies

In McCain Foods Limited v J.R. Simplot Company (2025 FC 1078), the Federal Court of Canada found that the Defendant’s use of pulsed electric fields (PEF) to pretreat potatoes before further processing into French fries did not infringe the Plaintiff’s Canadian Patent No. 2,412,841 (the “’841 Patent”). The Court found that the term “high electric field” as used in the asserted claims of the ‘841 Patent was limited to electric fields between 2-200 V/cm and did not encompass electric fields in the range of up to 1,000 V/cm or more, as typically used in PEF processing.

In the alternative, the Court found that if the asserted claims of the ‘841 Patent were construed to cover PEF processing of the sort used by the Defendant, then the asserted claims would be invalid on the basis of claim overbreadth and inutility.

The Court’s findings raise interesting points discussed in further detail below related to (i) the admissibility of expert evidence on the common general knowledge per se, (ii) claim construction, and (iii) invalidity, specifically claim overbreadth and lack of utility.

The Defendant, Simplot, was represented by Daniel Davies, Jean-Sebastien Dupont, Matthew Norton, and Emily Miller of Smart & Biggar’s litigation group.

Key takeaways

1. Expert evidence is admissible on the common general knowledge without construing the claims

At trial, the Defendant relied on expert evidence from Dr. Vorobiev. As part of his mandate, Dr. Vorobiev was asked to: (a) review the ‘841 Patent; (b) describe the skilled person of the ‘841 Patent, and (c) describe the common general knowledge (“CGK”) of the skilled person.1

The Plaintiff contended that since Dr. Vorobiev did not construe the claims of the ‘841 Patent, his opinion on the CGK lacked context and without this “complete picture” any evidence from Dr. Vorobiev regarding the prior art or CGK could not be helpful to the trial judge, since it was not connected to the ultimate issues to be determined by the Court.2

The Court held that, even though Dr. Vorobiev did not construe the claims, his evidence regarding CGK was clearly connected to the issue of claims construction as the Court approaches claims construction through the lens of the CGK.3 Accordingly, an expert’s evidence on the skilled person and their CGK can be relevant and admissible even if the expert does not opine on downstream legal issues. Among other reasons, the Court found support from Justice Binnie’s comments in Whirlpool that the role of the expert is “not to interpret patent claims but to put the judge in the position of being able to do so in a knowledgeable way.”4

2. “High electric field” was purposively construed based on the entire context in the ‘841 Patent

The infringement issues in the action turned substantially on the construction of the term “high electric field”, as used in claim 1. Specifically, claim 1 of the ‘841 Patent reads:

A process for treating vegetables and fruit before cooking in order to reduce their resistance to cutting, characterized by the application of a high electric field directly to the vegetables and/or fruit under conditions such that the resulting increase in the temperature of the vegetables and/or fruit is almost zero or at least sufficiently low as to not amount to a preheating step.  

The Defendant argued that the term “high electric field” in claim 1 does not encompass its impugned PEF process, which uses field strengths over 1000 V/cm applied in very short pulses (in the range of microseconds). The Plaintiff argued that “high electric field” should be broadly construed to encompass any electric field that makes fruits or vegetables easier to cut, and therefore covered the Defendant’s PEF process.5

The Court agreed with the Defendant that the term “high electric field” does not encompass PEF processing as used by the Defendant. Rather, a skilled person would understand the term as referring to a non-pulsed electric field in the range of about 2-200 V/cm.6

In arriving at this construction, the Court found that a skilled person would have understood that (i) “high electric field” is not a term of art, but a relative term used in various contexts to mean various things,7 and (ii) the prior art invariably used the term “pulses” when referring to PEF treatments, but no such references are found in the description of “high electric fields” in the ‘841 Patent.8

The Court further found that a skilled person reviewing the ‘841 Patent would see that the inventors discussed experiments using electric fields between 45-65 V/cm for 3-5 seconds and disclosed a preferred range of electric fields of 30-75 V/cm for 1-10 seconds. Further, a skilled person would see no indication that the inventors were teaching or claiming (i) electric fields 10-100X stronger than those discussed in the ‘841 Patent, or (ii) electric fields applied in short pulses up to 1 million times shorter than the shortest application period referred to in the ‘841 Patent.9

Based on this construction, the Court found that the Defendant did not infringe either of the asserted patent claims.

3. Invalidity of the asserted claims under the Plaintiff’s Construction

The Court also found that if the Plaintiff’s construction of “high electric field” were adopted, then the asserted claims are invalid for (i) being broader than the invention made or contemplated by the inventors, and (ii) inutility.

Specifically, the Court found that the inventors did not contemplate or soundly predict the utility of a process that involved the application of electric fields as high as 1,000 V/cm applied in pulses in the microsecond range (i.e. PEF treatments).10

The Court found that the differences between PEF treatments and the lower voltage non-pulsed electric fields studied by the inventors were not simply a question of the “degree” of treatment but a difference in the “kind” of treatment, including due to the different impacts such electric fields have on plant tissues, the different electrical parameters necessary for their implementation, and the different equipment required to apply them.11

The Court further noted a patentee cannot escape the requirement to soundly predict utility by “defining away” non-useful embodiments. The Plaintiff argued that claim 1 should be interpreted as being limited to only those electric fields that achieved the utility stated in the claim of reducing cutting resistance without improperly raising the temperature of the vegetable/fruit, such that the claim could not encompass any non-useful embodiments. The Court found that this approach was not viable, as it would replace the utility requirement with “a tautology that simply defines away” and disclaims any inoperable embodiments and would “effectively allow a patentee to obtain a monopoly on a result without teaching the particular means to achieve it,” contrary to the patent bargain.12

If you have questions or require further information, please contact a member of the IP Litigation & Enforcement group.

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References

  1. Dr. Vorobiev was also asked to comment on what a skilled person reading the ‘841 Patent would understand the patent is teaching in terms of the technology and its use (as disclosed and claimed in the ‘841 Patent), but the Court found those portions of Dr. Vorobiev’s evidence inadmissible.
  2. 2025 FC 1078, para 36.
  3. 2025 FC 1078, paras 37, 41.
  4. 2025 FC 1078, paras 37-38.
  5. 2025 FC 1078, para 3.
  6. 2025 FC 1078, paras 5-6, 219.
  7. 2025 FC 1078, para 224.
  8. 2025 FC 1078, para 225.
  9. 2025 FC 1078, paras 257-258.
  10. See, e.g. 2025 FC 1078, paras 381-386, 496-497.
  11. 2025 FC 1078, para 386.
  12. 2025 FC 1078, paras 454-455.