Focusing one's sights on invalid dependent claims

Here are the conclusions from a recent case in the Patents Court (the last two paragraphs of the judgment with some explanatory notes added by the IPKat for context).
228. As appears from my treatment of the issues above, I have concluded that Leica's challenges to the validity of the Patent fail [these challenges mainly being novelty and inventive step attacks on claim 1, as well as some sufficiency and added subject-matter issues]. I have also found that Leica's riflescopes infringe the Patent.

229. It may be that the findings that I have made demonstrate the obviousness of claim 3 of the Patent [this being a conventional dependent claim,” as claimed in claim 1 or 2”] from the IOR riflescope, but I will hear further argument on that point and also as to the consequences of my other findings, the relief to be granted, and as to costs.
The IPKat’s whiskers started to twitch reading these conclusions. His understanding is that conventionally, a dependent claim can save a patent where the independent claim lacks novelty or inventive step, but the opposite is rarely true. In other words, it is unusual for a dependent claim to be anticipated or obvious, while the independent claim basks in the warm glow of novelty and inventive step.

The judgment in which this finding was made is Swarovski-Optik v Leica Camera [2013] EWHC 1227 (Pat) and it runs to 229 paragraphs over 76 closely spaced pages. To be fair, about a third of the 76 pages are accounted for by a full translation of this German-language EP(UK) patent specification, and some lengthy quotations from the case law.

The IPKat believes this to be the first patent case to be decided by Mr Justice Vos in his capacity as a Nominated Judge of the Patents Court. It may also be his last, given his elevation to the Court of Appeal in March 2013. He is not entirely a stranger to the field of IP though, having decided a couple of trade mark and passing-off cases, notably United Air Lines Inc v United Airways Limited (discussed here), and Lady Gaga v Moshi Monsters (discussed here).

Unconventional dependent claims 

Back to the IPKat’s twitchiness. One can conceive of unconventional claims which are framed to appear dependent but in fact are not, e.g.
1. A room having walls, a ceiling, and a floor, and characterised by a light bulb within the room which is powered to provide illumination.

2. A room according to claim 1, in which there is no light bulb, and illumination is provided by a transparent window in the walls, floor or ceiling.

Patent attorneys are trained not to write claims in this way, but perhaps such cases could slip through the cracks once in a while. Faced with such a claim, one would expect judicial criticism of the claim’s clarity: how can the room of claim 2 be “according to claim 1” and yet omit the light bulb which is essential to claim 1? In construing claim 2 one would probably have to notionally rewrite it as a separate independent claim, sans lightbulb. Either way, it’s unusual and would normally occupy a good deal of reasoned comment if its validity were impugned.

The claims in Swarovski

A conventional riflescope. A distant, unthreatening animal (not shown) to the left, is rendered large, nearby and threatening to the eyeball on the right. Quick! Shoot it!
Claim 3 in Swarovski v Leica is not some sort of mutant claim which deletes or replaces a feature of the independent claim. It actually looks entirely conventional. The claims were directed to riflescopes which normally have an objective lens at one end, an eyepiece lens at the other end, and in between these one finds a system of internal lenses (labelled as the field lens and movable zoom relay lens elements in the diagram above) which magnify the image and turn it the right way up. On either side of the internal lens arrangement there are two positions where the object being viewed is in focus, these positions being “image planes”.

In the invention of claim 1, paraphrasing somewhat, an additional negative lens (coloured orange in the second diagram below) was provided to improve the image seen through the eyepiece. An important question of construction of claim 1 focused on (sorry) where this new lens was positioned, relative to the image plane 10 nearest the eyepiece 5.
The claimed riflescope with the extra lens shown in orange. What mattered was the position of this lens relative to the image plane (10)

In other words, did claim 1 require the lens 10 to be on the objective side of the image plane 10 (i.e. to the left, as shown above), or could it be on the eyepiece side (right) of that plane? The broader construction would have left the claims more vulnerable to attack based on the prior art and Leica argued for that interpretation.

Construction of the claims

Claim 1 did not mention the relative positions of the lens and the image plane, but it required that the new additional lens had to be “integrated in” the system of inverting, zoom lenses, and “disposed on the end of the inverting system facing the eyepiece”. The judge held that on its proper construction, this meant that the lens had to be
“at the end of the inverting system, but still as part of it [optically, if not mechanically], some way to the objective side of [the] second intermediate image [10]”.
Claim 3 seems at first glance to do little more than confirm this interpretation in different words:
3. Telescope or sighting telescope as claimed in claim 1 or 2, characterised in that the optical beam deflecting device [i.e. the negative lens] is disposed on the side of an eyepiece-end image plane (10) of the telescopic device pointing away from the eyepiece (5).
So claim 3 says that the lens is disposed on the side of the intermediate image plane (10) which points away from the eyepiece, i.e. the objective side. Claim 1 is construed by the judge to require this lens being positioned “some way to the objective side of the second intermediate image (10)”. Surprisingly (to this Kat at least), the judge concludes that claim 3 is “an alternative to claim 1”, based on a paragraph in the description which reads:
[0017] It has proved to be of practical advantage if the optical beam deflector device 2 is disposed on the side of the inverting system 1 facing towards the eyepiece 5. It is also advantageous if it is positioned on the side of the eyepiece-end image plane 10 facing away from the eyepiece 5. [The first sentence is essentially parroting an integer of claim 1; the second sentence is parroting claim 3]
Specifically, the judge found, that “claim 3 broadly mirrors the words used in the last sentence of paragraph 17, and is, as it seems to be, envisaging a different position closer to the second intermediate image than claim 1, but not on it [the image plane] or on the eyepiece side of it.”

Even after several readings this Kat is not entirely sure he follows the construction of claim 3, but his best interpretation of the judgment is that while claim 1 requires the negative lens to be “some way” from the image plane on the objective side, claim 3 also puts the lens on the objective side, but much closer to the image plane than the “some way” inferred from the construction given to claim 1. Confused yet? The IPKat certainly is, on the grounds that the exercise of construing the claims should lead to greater clarity rather than less, and if the scope of claim 1 hinges on the meaning of “some way from”, it is difficult to see how this allows the parties to understand what the boundaries of the claim are.

The conclusion that claim 3 is an alternative to claim 1 does not get a great deal of discussion in the judgment, and certainly is not presented as a surprising or unconventional interpretation (unless the IPKat has missed some nuance of the judgment).

The IPKat suspects and indeed hopes he is missing something crucial, and will be grateful to any readers who can provide their own thoughts on the construction given to claims 1 and 3.

Prior use and "normal usage"

There is more to this judgment than just this unusual issue of construction. Another finding which caused the IPKat to pause in his tracks was found in a discussion of prior use. The prior rifle scope had a negative lens (as in the invention) which normally was located to the right of the image plane, i.e. on the eyepiece side of it, rather than on the objective side as claim 1 was held to require. Interestingly, evidence was given that in some situations, such as when focusing on a close target with high zoom, the negative lens would inevitably be located slightly to the left of the image plane (in the position of claim 3 perhaps). The judge gave little weight to the fact that the prior use could be in this configuration, because one would not normally keep the lens in that configuration for hunting, and thus “in normal usage” the lens would be on the opposite side of the image plane, and outside the scope of the claims. It was not clear from the judgment if it was alleged (or disputed) that the prior art scope had, before the priority date, in fact been placed into the anticipatory configuration, and if so, whether that could be safely ignored because it was not normal usage.

What happens next? According to the final paragraph, the judge has yet to hear the parties on the claim 3 issue, or on the form of order to be made, but the IPKat will keep readers posted. In the meantime, please do add a comment if you make it through this longish judgment and come to a firm conclusion on how claims 1 and 3 have been construed.
Focusing one's sights on invalid dependent claims Focusing one's sights on invalid dependent claims Reviewed by David Brophy on Tuesday, May 21, 2013 Rating: 5


  1. David, thank you, an interesting post. Please, post more articles in this direction.

  2. While the issue here seems to be one of construction, there are cases (and I've dealt with one) where a strictly narrower dependent claim can be anticipated while the independent claim is not, due to priority dates.

    Suppose our applicant files an application in January, describing invention A. He then works out a better way of making it, and files a second application in June, claiming priority from the first but also describing B as a preferred (but not essential) feature. Claim 1 of this new application is to A, and claim 2 to A+B. Unfortunately, both A and A+B are described in a document published in March.

    Claim 1 is all right, as it is entitled to a priority date of January - the first application described A perfectly well to justify a claim to it in all its forms. But claim 2 has a priority date of June and is anticipated.

  3. To anon @ 23:27:00

    I hadn't considered that situation, but you're right of course.

    Needless to say, there were no priority considerations in this case. It seems to have been pure claim construction considerations that led the judge to consider claim 3 as an alternative to claim 1.


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