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PATENTS - Defences to infringement - Obviousness

Monday, August 19, 2019 @ 9:33 AM  


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Appeal by the defendant Tetra Tech from trial judgment finding that the respondent’s patents were not invalid due to obviousness and that appellant’s track inspection system infringed the respondent’s patents for track inspection systems. The respondent’s 082 Patent disclosed a system and method for inspecting railroad track. The 249 Patent disclosed a system and method for determining rail seat abrasion of a railroad track. The 249 Patent taught and claimed two distinct systems and methods for determining the presence and extent of rail seat abrasion.  The appellant, a competitor of the respondent in the field of machine vision systems for railroad track inspection, developed the Three-Dimensional Track Assessment System for inspecting railroad tracks. The appellant alleged that both patents were invalid because the subject matter of their claims would have been obvious to a person skilled in the art on the patents’ priority dates.

HELD: Appeal allowed. The Federal Court erred in failing to declare the 082 Patent to be invalid on the ground that it was obvious. The Federal Court erred in law by failing to consider and analyze how the skilled worker would have applied the common general knowledge to the prior art. The Federal Court never performed the exercise of looking at the prior art and seeing how the skilled worker, when faced with it, would have addressed the well-known challenges associated with the inspection of railway tracks and drawn from their common general knowledge. Had the Federal Court performed this exercise, it would have found that the differences between the prior art and the claims of the 082 Patent could be bridged by the skilled worker applying only the common general knowledge identified by the Court. Given the Federal Court’s finding that, prior to the priority date of the 082 Patent, machine vision and 3-D triangulation techniques, assisted by software, were available and commonly used to examine height differences of various surfaces, it was not inventive to use a machine vision system to detect and measure tie plate defects. While the Federal Court did not err in its conclusion that the application of a tilt correction factor was not an essential element of the patent claims respecting a method for determining rail seat abrasion of a rail road track in the 249 Patent, the Federal Court erred by failing to find that these claims were invalid on the ground that they were obvious. The claims for determination of rail seat abrasion did not require the determination of an actual delta based upon the application of a tilt correction factor. Instead, the system and method taught by these claims determined the difference in height between the rail base and the crosstie. The height differential was proportional to rail seat abrasion. The difference between the claims of the 082 Patent and the claims at issue of the 249 Patent was the reference point. For the 082 Patent the reference point was the height of the tie plate, for the 249 Patent it was the height of the rail base. There was nothing inventive at the time of the 249 Patent in choosing the rail base height as the reference point for calculating a height differential and determining rail seat abrasion. These claims of the 249 Patent were thus obvious and the Federal Court erred in failing to find those claims to be invalid.

Tetra Tech EBA Inc. v. Georgetown Rail Equipment Co., [2019] F.C.J. No. 789, Federal Court of Appeal, J.D.D. Pelletier, E.R. Dawson and W.W. Webb JJ.A., July 9, 2019. Digest No. TLD-August19019003