Verathon Medical (Canada) Ltd v Aircraft Medical Ltd.

Verathon Medical (Canada) Ltd v Aircraft Medical Ltd.[1]


A developer and manufacturer of medical devices (V), incorporated in Canada, alleged that a manufacturer of medical equipment (M) from UK infringed V’s patent in respect of an intubation instrument. V also sought for amendment of the patent.[2] M counterclaimed for revocation of the patent on the basis that V’s alleged invention was not new, lacked an inventive step and pleaded both anticipation and obviousness.

V’s patent sought to avoid the problem of manipulation of a patient’s head during intubation by indirect visualisation of the larynx through the use of a camera attached to an intubation instrument such as a laryngoscope. At the priority date of the patent there were two principal types[3] of laryngoscope in general use. It was clear from the patent’s description of the prior art that the invention was designed to improve the performance of laryngoscopes both in observation of the interior of the larynx and in intubation. Expert witnesses for V commented on the use by clinicians of both M and V’s products and noted that in each case, the device was inserted along the midline of the patient’s mouth with virtually no movement of the patient’s head; accordingly, the devices were used in substantially the same way.


V submitted inter alia that the phrase “substantially straight” should be construed by having regard to its normal English meaning and further, additional content should be read from its specific use and on the basis of how the skilled addressee would have understood it in its context in claim 1. The use of “substantially” as a modifier of “straight” meant that the phrase encompassed both a geometric straight line and a range of deviations from straight and the skilled addressee would give the phrase such a functional meaning.

M submitted inter alia that the prior art anticipated the patent and made obvious the alleged invention. The specification of the patent extended beyond that disclosed in the application therefore if the phrase “substantially straight” were to be interpreted as allowing the degree of curvature as sought by V, this amounted to added matter.


V’s approach to construction failed to take into account the range of geometric configurations. The emphasis throughout the claim was on the geometry of the device. There was no mention of function other than the reference to the lifter portion and the invention covered a range of devices in which the combination of the two portions could vary greatly. V’s construction of the expression “substantially” as a modifier of “straight” involved a departure from the normal use of words. Moreover, the use of the expression “substantially straight” was clearly a deliberate limitation of the claim.

M’s challenge to the validity of the patent failed on the court’s construction of claim 1 thereof, which emphasised the geometric descriptions of the device. Moreover the prior art did not make obvious the alleged invention in the patent and hence did not support M’s challenge to validity on the ground of obviousness.

V’s functional approach to the geometric descriptions in claim 1 was rejected and the anticipation challenge therefore failed.

Accordingly it was held that M’s product did not infringe the patent as neither V’s functional approach to the construction of key integers of claim 1 nor its inventive concept had been accepted, therefore the analytical superstructure erected thereon could not be accepted.

The proximal part of M’s product was not “substantially straight” but was clearly curved. Also, it was not at a defined angle to the lifter part as defined in claim 1 and the base portion was not to be seen as the part which V had equated therewith. The court observed that had V’s approach to the inventive concept been accepted, the invention could have been exposed to a possible challenge on the ground of obviousness on the basis of a combination of the common general knowledge of anatomically shaped blades and certain of the prior art.

Looking at the case from the perspective of interpretation of patent claims, other than para 23, 24 and 27, para 26 is noteworthy which is reproduced below-

First, the construction of the claims of a patent is an objective exercise. It is concerned with what the reasonable person, to whom the claims are addressed, would have understood the author of the patent to be using the words in the claim to mean.

Secondly, the notional addressee is the person skilled in the art who reads the specification with the common general knowledge of the art. The proper interpretation of the words of a patent is highly sensitive to the context and background against which the words are used, including the identity of, and knowledge attributed to, the skilled addressee.

“…Thirdly, the language which the patentee has used must be construed in the  context of the patent as a whole and in the light of that common general knowledge.

Fourthly, the skilled addressee in reading the patent assumes that its purpose is to describe and demarcate an invention. The notional addressee’s interpretation is purposive only in the sense that he approaches the patent in the knowledge that it is the communication of the idea of an invention.

Thus, fifthly, the language which the patentee has chosen is usually of critical importance. The words which the patentee uses in the specification, which is a unilateral document, will usually have been chosen upon skilled advice.

Sixthly, because a patentee is describing something which to his mind is new and for which there is not a generally accepted definition, the skilled addressee may readily see that he must have departed from conventional use of language or included in his description some element which he did not mean to be essential.

But, seventhly, one would not expect that to happen very often. A patent may, for one reason or another, claim less than it teaches or enables. And one would have to have some rational basis for concluding that the patentee had departed from conventional usage.

[1] [2011] CSOH 19; 2011 G.W.D. 14-346;

[2] Under the Patents Act 1977 s.75 and the Act of Sederunt (Rules of the Court of Session 1994) 1994 Sch.2 para.55.5(6)

[3] one had a curved blade and the other had a straight blade

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