IP monitor - Cry me a river: plaintiffs’ proposed claim construction leads to invalidation of asserted claims by the Gillette defence

The Federal Court invalidated the claims of a patent asserted in an infringement action, finding the plaintiffs’ choice to advance a broad construction invited the unavoidable validity problems that these claims are obvious and lack novelty.

In TearLab Corporation v I-MED Pharma Inc., the defendant I-MED Pharma Inc. prevailed in an action for patent infringement, in which I-MED’s i-Pen® Osmolarity System was alleged to infringe certain claims of Canadian Patent No. 2,494,540 (the 540 Patent). The court found some of the claims to be infringed, but held that all the asserted claims of the 540 Patent were invalid by being anticipated or by being obvious in light of the prior art, due to the plaintiffs’ choice to construe the claims of the 540 Patent broadly so as to capture the i-Pen® Osmolarity System.

The 540 Patent

The 540 Patent is related to measuring the osmolarity of a sample of bodily fluid, particularly tear film, that is deposited on a chip, where the sample fluid operatively covers the sample region of the chip. Electrical, optical or thermal energy imparted to the sample fluid is then detected to produce an output signal that indicates osmolarity of the sample fluid. The 540 Patent also discloses an osmolarity measuring system that receives an output from a reception device, then interprets it and displays an osmolarity value to the user.

The i-Pen® Osmolarity System and the single-use sensors

The i-Pen® Osmolarity System measures the conductivity of the tear-soaked eyelid conjunctiva and correlates this measurement to osmolarity. A single-use sensor, consisting of a pair of electrodes on a non-conducting substrate, is inserted into the i-Pen® Osmolarity System and placed against the moist tissue on the inner eyelid conjunctiva. The tear-soaked conjunctiva completes an electrical circuit between the electrodes when an electrical current is applied, and the conductivity is then measured by a microprocessor within the i-Pen® Osmolarity System. An osmolarity reading is then displayed on an LCD screen.

The patent’s claims are not restricted to in vivo or ex vivo applications

The court held that the sample receiving chip in the 540 Patent comprises a substrate that receives an aliquot volume of a sample fluid and a sample region where energy properties of the sample fluid can be detected. Justice Manson found that the chip could be as simple as two electrodes on a non-conducting substrate without the need to perform onboard calculations, apart from a single claim that requires an onboard processing unit. He also found that the sample receiving chip is not limited to conducting osmolarity measurements that are substantially independent of the sample fluid volume, and also is not required to have properties such as rigidity, planarity and integrated electrodes.

The court held that the asserted claims are not limited to ex vivo applications, despite the ex vivo examples in the patent and the patent’s distinguishing of in vivo prior art in its introductory section. Use of the term “aliquot volume” also does not restrict the patent to ex vivo applications, as it does not matter whether the sample fluid is placed on the substrate or whether the substrate is placed in the sample fluid.

The Gillette defence

Among its defences, I-MED asserted non-infringement on the basis of the Gillette defence. The Gillette defence pleads that the allegedly infringing device practises the prior art, thus placing a plaintiff on the horns of a dilemma. If there is infringement then the asserted patent is invalid by being anticipated by the prior art, and if the patent is valid then there is no infringement.

Justice Manson agreed none of the asserted claims of the 540 Patent would be infringed if the claims were limited to ex vivo applications. However, based on his construction that the claims were not limited in this way, he found that the i-Pen® Osmolarity System and the SUS infringe certain claims of the 540 Patent. Justice Manson then pointed out that the unavoidable validity problems of anticipation and obviousness are invited by the plaintiffs’ position that the 540 Patent covers both in vivo and ex vivo applications for any bodily fluids without limitations. He found that certain asserted claims of the 540 Patent are anticipated by in vivo devices disclosed in the prior art that correlated electrical conductivity of a sample fluid with osmolarity.

The court chose not to comment on whether the Gillette defence applies to obviousness. However, Justice Manson held that all the 540 Patent’s asserted claims are invalid for being obvious. He found that a person of ordinary skill in the art would combine prior art referring to ex vivo means of measuring conductance with anticipatory prior art to create a device that can be used both in vivo and ex vivo, including a separate or onboard processing unit to measure osmolarity of tear fluid.


The court followed the Supreme Court of Canada’s 2017 decision in AstraZeneca Canada Inc v Apotex Inc, 2017 SCC 36 that a mere scintilla of utility is sufficient to satisfy the requirement that a patented invention be useful. Justice Manson held it was sufficient the inventor was able to obtain stable osmolarity readings from a prototype device by the Canadian filing date, even though the device was not perfected and there was no demonstrated or predicted utility for measuring other bodily fluids.

Alleging infringement based on a broad claim construction risks invalidation by anticipation and obviousness

This decision demonstrates the danger of bringing an action for patent infringement that relies on a broad claim construction in order to capture allegedly infringing activities within the scope of the patent’s claims, particularly if the defendant’s activities are practicing the prior art. A finding of infringement is likely to bring a concurrent finding that the asserted claims are invalid in light of the prior art.

Norton Rose Fulbright acted as counsel to I-MED Pharma Inc.

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