You Can’t Have the Claim Construction Cake, and Eat the Validity Cake Too

Arctic Cat Inc v Bombardier Recreational Products Inc 2016 FC 1047 Roy J
            2,322,738

In Arctic Cat v BRP Roy J held that Arctic Cat’s 738 patent was not infringed by BRP’s snowmobile engines. This holding turned primarily on the construction of the claims. Roy J also held that if he was wrong as to the proper claim construction, so that BRP’s engines did infringe, then the claims at issue were invalid for obviousness. The analysis raised no new issues of law, but it does illustrate the interaction between claim construction, validity, and infringement. The patentee was trying to argue for a broad construction for infringement and a narrow construction for validity, which made it difficult to mount a consistent argument on either point.

In a gas engine, a spark causes the fuel to ignite in a compressed gas / air mixture, which then expands, driving the piston around its cycle. Setting the point in the cycle at which the spark ignites (the “ignition point”) is referred to as ignition timing. Since the spark normally occurs before the piston reaches the top of the compression stroke (“top-dead-centre” or “TDC”), the timing is described as the number of degrees of rotation before TDC [22]. Ignition timing affects engine power and efficiency. While in a very basic engine the ignition timing might never vary, it is more usual for the ignition timing to vary, potentially depending on several factors. The most fundamental is for the ignition timing to vary with the engine speed (RPM). The optimal timing may also vary with a variety of other factors, such as fuel octane rating, throttle position or altitude. The 738 patent relates to an two-stroke engine in which the ignition timing varies depending on the temperature of the exhaust gas.

A difficulty facing Roy J is that it was never very clear what was actually invented [281]. The named inventor was of the view that the invention was the broad idea of adjusting the ignition timing based on the exhaust temperature [278], [279]. Roy J held that if this was indeed the correct construction of the claims, the claimed invention was obvious over two different items of prior art that disclosed the same concept [282], [286]. The distinguishing elements of the asserted claims, such as use in a snowmobile engine, were not enough to render the 738 patent non-obvious [283]. This aspect of the decision was quite straightforward and turned on the facts.

In any event, Roy J was of the view that, properly construed, the claims were not so broad as to cover all embodiments of the concept of adjusting ignition timing based on the exhaust temperature. The claims all refer to the ignition point being selected from a plurality of different “ignition patterns,” where the particular pattern is based on the exhaust temperature. An ignition pattern gives a set of ignition timing point mapped against engine speed according to the engine speed (eg the ignition pattern for 400C might specify the following mapping of (RPM, Angle): (8400, 11.0), (8200, 11.5), (8000, 13.0), (7750, 15.0) etc [23]). Selecting a different ignition patterns according to the exhaust temperature, amounts to selecting a different mapping of ignition timing to RPM. Roy J held that the use of the exhaust temperature to select an ignition pattern, not the ignition point, was essential to the invention [206], [234], [243].

This was crucial to the infringement issue. BRP’s engines used a formula to adjust the ignition timing [224]. The formula did apply an adjustment based on exhaust temperature, along with other adjustments (such as throttle position and altitude), and this adjustment did (apparently) vary with the engine speed [224]. However, the method used in BRP’s engines did not select an ignition pattern according to temperature and then make other adjustments. Instead, the adjustment was made on a point-by-point basis. Thus, even though the BRP engines did adjust ignition timing according to exhaust temperature, on Roy J’s claim construction, they did not infringe [246], [247]. Put another way, if I understand correctly, if BRP’s engine had selected the ignition pattern based on exhaust temperature first, and then made the other adjustments, it would have infringed, but because it selected an ignition pattern based on throttle and altitude first, and then adjusted for exhaust temperature, it did not infringe, even though the actual final ignition timing for a given set of parameters might be exactly the same in either case.

This might seem formalistic and maybe it is. It’s difficult to say because it’s not clear what the actual inventive contribution might have been. Suppose (counter-factually to Roy J’s finding on obviousness), that the inventor had indeed been the first to think of the very concept of basing ignition timing on exhaust temperature. In that case I would be very sympathetic to the view that the exact order in which the ignition point was selected should not matter, despite the reference to “ignition pattern” in all the claims, on the principle expressed in Consolboard [1981] 1 SCR 504, 520-21, that “[t]here is no occasion for being too astute or technical in the matter of objections to either title or specification for, . . . ‘where the language of the specification, upon a reasonable view of it, can be so read as to afford the inventor protection for that which he has actually in good faith invented, the court, as a rule, will endeavour to give effect to that construction’.” On the other hand, suppose it was well known in the prior art that ignition timing should be adjusted based on exhaust temperature, but no one had ever thought of it being done by selecting an entire ignition pattern based on temperature (which might have some processing speed advantage). In that case, it would certainly be appropriate to construe the claims as turning on the particular step at which the ignition pattern was selected.

The difficulty is that what it was that the inventor had actually invented was never set out as part of the claim construction analysis. That omission is by no means unique to this case. But it is difficult to see how the court can endeavour to give effect to a construction protecting that which was actually invented, if we never know what it was that was actually invented. Of course, it may be that the words of the claim cannot be stretched far enough to cover what was actually invented, in which case the failure of the claim would be a “self-inflicted wound” Free World Trust 2000 SCC 66, [51]. But the conclusion that the inventor has misspoken itself supposes that we have purposely construed the claims in the first place: “The public is entitled to rely on the words used provided the words used are interpreted fairly and knowledgeably” [51, original emphasis].

I don’t want to make too much of this point in this particular case. Roy J complained that “[a]s indicated on numerous occasions during the trial, what was truly invented in this case remains somewhat nebulous” [281]. Roy J cannot be faulted for not have considered what was actually invented if the patentee did not explain it. It seems that the patentee’s vagueness on this point stemmed from the fact that it was trying to argue for a broad construction to prevail on infringement, while at the same time arguing for a narrow construction in order to prevail on non-obviousness [307]. It is not surprising that this schizophrenic approach to the inventive concept should have made the claim construction exercise particularly difficult, and in the end, the patentee lost on both points. Of course, given the patent and the prior art, a more focused approach would probably also have ended in defeat for the patentee.