Like legislation in many jurisdictions, the Canadian Patent Act requires a claimed invention to be useful. However, a detailed examination of utility seldom arises in infringement actions involving mechanical patents because the usefulness of the subject matter of such patents is usually apparent from the specification and drawings of a properly drafted application. Nevertheless, the recent Federal Court decision in Eurocopter v Bell Helicopter Textron Canada Limitée(1) illustrates the risk of including a promise in a mechanical patent specification where the utility for the full scope of the claimed subject matter cannot be demonstrated or soundly predicted at the application filing date.
In 1981 the Supreme Court of Canada held that 'not useful' in patent law means that the invention will not work, either in the sense that:
- it will not work at all; or
- it will not do what the specification promises that it will do.
Therefore, while the threshold for the utility standard in Canada is generally low, a promise in the specification can elevate the utility standard to require fulfilment of those promises by all of the embodiments that are encompassed by a claim. Those promises may invalidate a claim unless the promised utility is demonstrated or can be soundly predicted as of the Canadian filing date.
'Sound prediction' of utility evolved as an alternative to demonstrated utility in pharmaceutical contexts of Canadian law. Even if a claim to a pharmaceutical did not have demonstrated utility by the Canadian filing date, the claim could nevertheless satisfy the utility requirement if the specification disclosed a factual basis from which utility could be predicted based on a sound line of reasoning. While a detailed examination of sound prediction seldom arises in connection with a mechanical patent for the reasons mentioned above, the Eurocopter decision signals the potential applicability of sound prediction where the field of the invention is complex and involves significant testing, such as the development of helicopter landing gear.
Eurocopter involved the development of landing gear pertinent to helicopters with three or four blades. Helicopters with three or four blades must be designed to avoid ground resonance instability, which can result from the mode of the helicopter's rotor coupled with motion of the helicopter on its landing gear. Prior art solutions to ground resonance instability included piston dampers, but such dampers add weight, require maintenance and can cause other disadvantages. To avoid dampers, the Eurocopter patent claimed landing gear that could absorb forces in two different planes. More specifically, the claims of the Eurocopter patent included a single independent claim and 15 dependent claims, which were directed at a helicopter landing gear, including an integrated front crosspiece offset either forwards or backwards relative to the front of the ground contact surfaces.
While there was no serious dispute that Eurocopter's claimed invention was useful for certain purposes, the court found that the specification specifically promised to reduce drawbacks of the prior art landing gear, such as elevated load factors and weight, and further to allow helicopter manufacturers to reduce costs and mix flexibility with ground resonance safety. The court went on to find that, as of the Canadian filing date, the applicant had no evidence that a backwards offset provided any ground resonance advantage. Moreover, no calculations or tests had been performed before the Canadian filing date to determine the effect of this configuration on ground resonance, and thus there was no data to provide the factual basis for a prediction that the variant would provide such utility. Accordingly, the court found Claims 1 to 14 and 16 invalid insofar as they captured embodiments having a backwards offset front crosspiece. In reaching its conclusion, the court accepted the testimony of the defendant's expert witness that a person skilled in the art would think that landing gear having a backwards offset front crosspiece might be more vulnerable to buckling on impact.
The court did find that the promised utility had been demonstrated for embodiments wherein the front crosspiece was offset forwards, as specifically recited in Claim 15, and that this single remaining dependent claim was infringed by the defendant's landing gear.
In following Canadian pharmaceutical decisions regarding sound prediction, the court in Eurocopter held that actual utility will not necessarily satisfy the utility requirement; bare speculation, even if it turns out to be correct after the fact, is insufficient to justify a valid patent. Accordingly, the court held that it is unnecessary for a party challenging a patent to prove that the invention will not work, or that it will not do what the specification promised it will do. Rather, the party merely needs to show that the specification contains no evidence or data to support a prediction with respect to the promised utility of particular embodiments. In so holding, the court added to the potential dangers of promises in a specification, because the court would seemingly invalidate a mechanical claim for lack of utility even where the promised utility was, in fact, subsequently demonstrated after the Canadian filing date.
The Eurocopter decision highlights that lack of utility attacks are not limited to pharmaceutical patents, but can extend to any subject matter. Caution should be taken in making any promise of the usefulness of an invention that has not been demonstrated or cannot be soundly predicted when the application is filed.
The Eurocopter decision is currently under appeal; a decision by the Federal Court of Appeal is not expected for several months.
For further information on this topic please contact Jonas H Gifford at Smart & Biggar/Fetherstonhaugh by telephone (+1 604 682 7780), fax (+1 604 682 0274) or email ([email protected]).