2,587,065 / I-LOCK and X-LOCK quick coupler
This infringement action ultimately turned entirely on claim construction. A key issue in claim construction was whether recourse to the disclosure was permissible; in the course of coming to opposite conclusions, the defendant’s expert started with the disclosure and relied extensively on it in construing the claims, while the patentee’s expert largely ignored the disclsoure. Southcott J began his discussion of claim construction by quoting the principle that recourse to the disclosure is “unnecessary where the words are plain and unambiguous”. As discussed below, Southcott J evidently took this as saying that recourse to the disclosure in claim construction is permissible only when the claims are ambiguous. In my view, that proposition is clearly wrong. Since Southcott J found the claims to be ambiguous, and hence recourse to the disclosure was permissible, the error made no difference to the result. Nonetheless, because Southcott J’s view was based on FCA authority, the point warrants some discussion.
Cascade’s 065 patent relates to a safety locking device for quick couplers, devices which are used with machines such as excavators to allow quick attachment and removal of implements at the end of the excavator arm . The coupler attaches to the implement by means of a front pin and a rear pin, and there is a safety locking mechanism for each pin. The locking mechanism in the coupler described by the patent is hydraulically operated, and the patent claims a coupler
wherein the safety locking device of the hook portion is configured to release the front pin by being moved into an unlocked position using a hydraulic circuit which operates independently of the hydraulic locking mechanism of the mounting portion.
The patentee’s embodiment of the invention, the I-LOCK couple , as well as the embodiment described in the patent , use separate hydraulic lines to disengage the front and back pin locking mechanisms. The unlocking mechanisms operated “independently” in that sense. The defendant Kinshofer’s accused device, the X-LOCK, used one hydraulic line to disengage both locking mechanisms. At low pressure neither unlocking mechanism is affected; as the pressure increases, the back pin mechanism is unlocked; and at even higher pressure, the front pin mechanism is unlocked . This was referred to as “pressure modulation.” The central question was whether the claims, properly construed, encompassed the X-LOCK mechanism. This turned on whether the pressure modulation system meant that the front and back circuits operated “independently.” Without going into the details, suffice it to say that the disclosure made it amply clear that the if the mechanisms were hydraulically connected, they did not operate independently, despite the pressure modulation -. In coming to opposite conclusions, Kinshofer’s expert, Mr Weller, relied extensively on the disclosure in construing the claims , while Cascade’s expert, Mr Johnson, largely neglected the disclosure , . Thus an important question was whether it was proper to have recourse to the disclosure in construing the claims.
Southcott J began at  with the summary of claim construction principles from Monsanto v Schmeiser, 2002 FCA 309, :
It is also well settled that in construing the claims of a patent, recourse to the disclosure portion of the specification is (1) permissible to assist in understanding the terms used in the claims, (2) unnecessary where the words are plain and unambiguous, and (3) improper to vary the scope or ambit of the claims: Dableh v. Ontario Hydro (C.A.),  3 F.C. 751 [1996 CanLII 4068] at paragraph 30, leave to appeal refused,  S.C.C.A. No. 441 (QL).
Southcott J took point (2) seriously. He was somewhat critical of Mr Weller for having devoted considerable time to reviewing the disclosure before having turned to the claim language , saying “I would have preferred to see a focus upon the meaning of the claims in the Patent before turning to interpretation of the disclosure, to ensure that the jurisprudential principles surrounding claim construction have been respected” . In the end, Southcott J did rely on the disclosure to construe the claims -, but only after having taken pains to establish that the term “hydraulic circuit” is ambiguous, so therefore “it was permissible for [Mr Weller] to have recourse to the disclosure to assist in understanding the meaning of this term” , and similarly that the term “hydraulic locking mechanism of the mounting portion” was also ambiguous, so that again, recourse to the disclosure was permissible and necessary .
Thus, it seems that Southcott J was of the view that recourse to the specification is impermissible unless the claim is ambiguous. That view is entirely understandable, as it has the support of point (2) in Dableh and Monsanto. Nonetheless, it is incorrect. The issue arose in Pfizer v Apotex / quinapril 2007 FCA 209, in which Pfizer’s expert gave considerable importance to the disclosure, and Apotex’s expert, Dr. Langer, asserted that “it was wrong of [Pfizer’s expert] to interpret claim 1 of the ‘615 patent in the light of the specification because claim 1 is clear and unambiguous” . The FCA rejected this:
 In my view, Dr. Langer’s approach is incorrect. In Whirlpool, [2000 SCC 67], Binnie J. at paragraphs 49(e) and 52 made it clear that claims were to be construed in light of the entire specification in order to enable the reader to properly understand the claim at issue, bearing in mind that the specification could not serve as a device to expand the patentee’s monopoly.
It might be said that if the claims are plain and unambiguous, it is at least “unnecessary” to have recourse to the disclosure, even if not strictly impermissible. However, the FCA went on to note that:
 In expressing this opinion, Binnie J. referred to the remarks of William L. Hayhurst found in The Art of Claiming and Reading a Claim, J.F. Anderson editor, Patent Law of Canada, Scarborough, Ontario, Carswell, 1994, 177, made at page 190, to the effect that it was often unsafe to conclude that a term in a claim was plain and unambiguous without having carefully reviewed the specification.
Thus, we cannot know whether it is unnecessary to look to the disclosure without having first looked to the disclosure.
The point that it is always permissible, and indeed necessary, to look to the disclosure was reiterated by the SCC in Monsanto 2004 SCC 34, :
Purposive construction of patent claims requires that they be interpreted in light of the whole of the disclosure, including the specifications. . .
While the SCC in Monsanto seems to have confused the “disclosure” and the “specification,” the point is nonetheless clear when read in context and in light of the authorities cited. Like the FCA in Quinapril, the SCC in Monsanto cited Whirlpool for this proposition, and also Consolboard  1 SCR 504, 520, where the SCC stated that “We must look to the whole of the disclosure and the claims to ascertain the nature of the invention and methods of its performance.” (Whirlpool at  also cited this passage from Consolboard.) For that proposition the SCC in Consolboard in turn in cited Minerals Separation  SCR 36, where the SCC, at 56, stated that “It is well settled that the specification is to be read as a whole and the claims, of course, are part of the specifications.” And in Minerals Separation, the SCC quoted Lord Russell’s discussion in EMI v Lissen, at 39, as “[p]erhaps the most authoritative statement” regarding claim construction, including the following statement (my emphasis):
The claims must undoubtedly be read as part of the entire document and not as a separate document; but the forbidden field must be found in the language of the claims and not elsewhere.
The same point is repeated in Metalliflex  SCR 117, 122: “The claims, of course, must be construed with reference to the entire specifications, and the latter may therefore be considered in order to assist in apprehending and construing a claim, but the patentee may not be allowed to expand his monopoly specifically expressed in the claims ‘by borrowing this or that gloss from other parts of the specifications’.”
Thus the highest authorities are entirely consistent with Lord Russell’s succinct and venerable statement of the law. His statement is reflected in points (1) and (3) in the Dableh summary, but it is inconsistent with point (2), at least if point (2) is interpreted as meaning that recourse to the disclosure is impermissible when the claim is unambiguous. Lord Russell’s statement is also entirely sound as a matter of principle. As the SCC pointed out in Minerals Separation, the claims are part of the specification, and it is the specification which is addressed to a person skilled in the art. The skilled person must read the text of the claims in light of its context and purpose. Part of the context is the skilled person’s common general knowledge; why should the skilled person read with that context in mind, while ignoring the context that is most directly relevant to the claims, namely the disclosure, which is actually part of the same document?
So where does point (2) come from? It can be traced through Dableh, to Beecham v Procter & Gamble (1982), 61 CPR(2d) 1 (FCA), and thence to Electric and Musical Industries Ltd. v Lissen (1939), 56 RPC 23 (HL). In Beecham the FCA quoted a long passage from Lord Russell’s opinion in EMI v Lissen in which Lord Russell noted that the role of the claims is to define the scope of the monopoly. He then stated at 41:
If the patentee has done this in a claim the language of which is plain and unambiguous, it is not open to your Lordships to restrict or expand or qualify its scope by reference to the body of the specification.
While this is a different passage than had been quoted by the SCC in Minerals Separation, Lord Russell is making the same point. The FCA quoted further from the same discussion, with emphasis:
The same view was expressed by Romer LJ in the following felicitous language in British Hartford-Fairmont Syndicate Ltd v Jackson Bros (Knottingley) Ltd, [(1932), 49 RPC 495 (HL)] at p 556:
One may, and one ought to, refer to the body of the specification for the purpose of ascertaining the meaning of words and phrases used in the claims or for the purpose of resolving difficulties of construction occasioned by the claims when read by themselves. But where the construction of a claim when read by itself is plain it is not in my opinion legitimate to diminish the ambit of the monopoly claimed merely because in the body of the specification the patentee has described his invention in more restricted terms than in the claim itself.
This is evidently the inspiration for the statement that recourse to the disclosure is unnecessary when the words of the claim are plain.
However, Lord Russell’s opinion cannot be read as saying that recourse to the disclosure is impermissible unless the claims are ambiguous. This is inconsistent with his statement that “The claims must undoubtedly be read as part of the entire document and not as a separate document.” Indeed, the following passage, at 41, explicitly supports the contrary proposition:
I would point out that there is no question here of words in Claim 1 bearing any special or unusual meaning by reason either of a dictionary found elsewhere in the Specification or of technical knowledge possessed by persons skilled in the art. The prima facie meaning of words used in a claim may not be their true meaning when read in the light of such a dictionary or such technical knowledge; and in those circumstances a claim, when so construed, may bear a meaning different from that which it would have borne had no such assisting light been available.
This is saying that even when the claims are plain on their face, the disclosure may show they have a different meaning, and in such a case it is necessary to look to the disclosure to discern their "true" meaning. This is the same point as was made by the SCC in Whirlpool, and reiterated by the FCA in Quinapril. Thus, contrary to point (2) from Dableh, it is always necessary to have recourse to the disclosure to construe the claims, even when the claims appear plain on their face. Accordingly, immediately after addressing the general principles of claim construction, Lord Russell began his discussion of the patent at hand by saying “I have read and re-read the specification many times and with much care.” There is no suggestion that he read the disclosure only after trying to construe the claims and finding them ambiguous.
Moreover, the statement by Romer LJ that was quoted by Lord Russell and emphasized in Beecham would be equally true without any reference at all to the claims being "plain"; whether the claims are plain or ambiguous, it is never “legitimate to diminish the ambit of the monopoly claimed merely because in the body of the specification the patentee has described his invention in more restricted terms than in the claim itself.” That is point (3) from Dableh. As Lord Russell noted, Romer LJ was expressing “the same view” as Lord Russell was in saying that when the language is plain “it is not open to your Lordships to restrict or expand or qualify its scope by reference to the body of the specification.” So, in the underlined passage Romer LJ is not saying that recourse to the disclosure is unnecessary in order to construe the claim; he is saying that recourse to the disclosure is not legitimate to vary the claim. That is the difference between point (2) from Dableh, which is not consistent with Lord Russell's opinion, and point (3) from Dableh, which is.
In British Hartford-Fairmont Romer LJ actually began his analysis with the disclosure, as did Mr Weller in this case. The disclosure was extremely poorly drafted and very difficult to understand (553-56). Claim 1 was actually more clearly worded than the disclosure (556), and the construction advanced by the patentee sought to alter the language beyond what it could bear. This was the context for Romer LJ’s statement. In context, as well as on its face, it speaks against varying the claims by reference to the disclosure, not against construing the claims by reference to the disclosure.
The FCA cases cited for point (2) do affirm the proposition, but in neither case was it necessary to the result. In Beecham the FCA held that recourse to the specification was unnecessary (15-16), but went on to say that recourse to the disclosure would support the same conclusion in any event (16). The FCA in Dableh held that “the Trial Judge erred in construing the meaning of the terms varying electric current and electromagnetic coil by reference to the embodiments illustrated and described in the disclosure of the patent. The terms are not ambiguous, and on their face encompass AC current and coils other than the type used by the appellant. In doing so he committed an error in law.” This could be taken to suggest that the trial judge erred by using the disclosure to construe claim terms that were unambiguous. But the FCA also held expressly that the trial judge’s construction of the terms in question was in error even if recourse was had to the disclosure. The trial judge’s real error lay in confining claims to the embodiments specifically described in the specification. It is very well established that the claims need not be confined to the embodiments which are specifically disclosed, and to so restrict them is to use the disclosure to vary the scope of the claims. That is quite different from using the disclosure to construe the claims. The FCA in Dableh also cited Unilever v Procter & Gamble (1995), 61 CPR (3d) 499 (FCA). In Unilever Stone JA did state that “If the words of a claim are clear, it is necessary to look no further to discover the nature of an invention; otherwise, resort may be had to the disclosure for assistance in comprehending the meaning of words used in the claims.” However, this proposition played no role in his reasoning, as both the trial judge and the FCA quoted at length from the disclosure in the course of construing the claims.
In summary, it is strictly incorrect to say that it is unnecessary to have recourse to the disclosure where the words of the claim are plain and unambiguous. It is always necessary to read the specification as a whole, if only to decide whether the claims are ambiguous. Certainly, when the claims are clear, reading the disclosure is unlikely to result in a different interpretation, but the point remains that is never improper to read the disclosure before reading the claims, and it is never improper to construe the claims in their context, including the disclosure. The true rules are stated in points (1) and (3) from Dableh, though EMI v Lissen says it just as well: “The claims must undoubtedly be read as part of the entire document and not as a separate document; but the forbidden field must be found in the language of the claims and not elsewhere.”