In McCain Foods Limited v. J.R. Simplot Company, the Federal Court of Appeal dismissed McCain Foods’ appeal of a Federal Court’s decision concerning alleged infringement of McCain Foods’ Canadian Patent No. 2,412,841.

The patent claims a process for treating vegetables, including potatoes, using a “high electric field” to reduce resistance to cutting without preheating or cooking them. The trial judge had found that J.R. Simplot’s pulsed electric field systems, which operate at 1,000 volts per centimetre or more, did not infringe the claims. The trial judge construed the term “high electric field” in the claims as referring to fields in the range of 2 to 200 V/cm. In the alternative, the trial judge held that if the claims were construed to cover fields so far beyond this range as to cover the electric fields used by J.R. Simplot, the claims would be invalid for both overbreadth and lack of utility.

On appeal, McCain Foods challenged the trial judge’s interpretation of the term “high electric field,” arguing that it led to reviewable errors in law related to the conclusions on infringement and validity.

The Federal Court of Appeal held that, “because the Federal Court’s claim construction was based on its appreciation of the expert evidence”, the trial judge’s construction attracted deference, and it was not satisfied that a palpable and overriding error had been made. The Court of Appeal thus upheld the finding that a person skilled in the art would understand the claims to include such a numerical limit to the term “high electric field.” Having found no infringement, the Court of Appeal declined to address issues of validity.

The full decision can be found here.