Convatec v Smith & Nephew: why the Court of Appeal was wrong

There's definitely something wrong ...
The IPKat has reported already twice on the interesting Court of Appeal, England and Wales, decision in Smith & Nephew Plc v ConvaTec Technologies Inc, relating to ConvaTec's patent EP (UK) 1,343,510 relating to silverised wound dressings (see Jeremy here, and this Kat here).  The Court of Appeal, reversing the first instance decision of Mr Justice Birss, held that a patent process claim that specified an "agent being present in a concentration between 1% and 25%" was infringed by Smith & Nephews's modified process in which the agent was present in a concentration of 0.77%.

This Kat was troubled by the decision, as he thought that the first instance decision was basically correct.

The Court of Appeal decision delivered by Lord Justice Kitchin considered what the description of the patent said about the concentration of the agent at [0028]:
The quantity of agent used will depend upon the amount of polymer-containing material being prepared and the total volume of solution. Preferably, the agent is present in a concentration between .01 and 50% of the total volume of treatment. In some embodiments, the concentration of agent is between .01-25%, .01-10%, .01-5%, .1-5%, .1-25%, .1-10%, 1-25%, 1-10%, 1-5%, 5-25%, 10-25%, or 25-50% of the total volume of treatment.
This paragraph, and the fact that the 1-25% range was introduced into claim 1 of the patent in the previous litigation proceedings between the parties, was key to Kitchin LJ's decision, as can be seen from the following three paragraphs from the judgment.
Second, it is apparent from the body of the specification that the patentee had well in mind the possibility of expressing numerical values with a very high degree of precision. Thus, in paragraph [0023], the patentee has identified a series of different silver concentration ranges using limits expressed, on some occasions, to an accuracy of zero decimal places but, on other occasions, to an accuracy of one decimal place. Similarly, in describing the permissible ranges of binding agent concentration in paragraph [0028], the patentee has used limits expressed with degrees of precision which range from zero decimal places to two decimal places. I believe this to be a powerful factor in favour of the interpretation of the claim for which ConvaTec contends. Against this background, I think the skilled person would understand that the patentee has chosen to express the numerical limits of the range in the claim to only a limited degree of accuracy.
Third, the reader is taught by paragraph [0028] and from the example at the end of the specification that the invention can (and preferably should) be performed with a binding agent concentration between 0.01 and 50%. This is a very wide range and it extends significantly beyond the limits of the claim. Once again this is a factor which undermines Smith & Nephew's favoured interpretation of the claim. It teaches the skilled person that there is no technical reason to read the claim as requiring the use of a binding agent concentration which falls between the exact numerical values of 1% and 25%.
... or thereabouts?
Fourth, I recognise that the concentration limits which appear in the claim have in a sense been chosen by the patentee as opposed to calculated by him or determined by experiment. Further they have been introduced into the claim by amendment. These are both matters upon which Mr Mellor has placed particular reliance but I do not believe they take him very far. However the patentee may have derived the numerical limits, the skilled reader seeking to put the invention into practice or satisfy himself that his process falls outside the scope of the claim must calculate his binding agent concentration or measure it. Either way he must do so with a particular degree of precision and the question is still whether the reader would understand the patentee intended the 1% and 25% limits of the claim to be understood as exact values or in a less precise way.
In the earlier consideration of this decision, I wrote:
This Kat wonders what has happened to the doctrine that "what is not claimed is disclaimed" - there is surely an argument that if it is taught that the invention can be performed with a binding agent concentration between 0.01 and 50%, but what is claimed is narrower, then this narrower range should be given a strict interpretation.  Yet Kitchin LJ took the opposite view - "Once again this is a factor which undermines Smith & Nephew's favoured interpretation of the claim."
But there is a further fact that seems to fatally undermine the reasoning in the three quoted paragraphs above, and that is that paragraph [0028] should not be in the amended patent at all.

Why not?

Well, practitioners before the European Patent Office will be well aware that, when a claim is narrowed during prosecution or post-grant in opposition proceedings, it is invariably required that the description be amended accordingly, and statements that go outside the scope of the amended claims should be excised.  Section 75(5) of the Patents Act 1977 states:
In considering whether or not to allow an amendment proposed under this section, the court or the comptroller shall have regard to any relevant principles applicable under the European Patent Convention.
Not Court of Appeal policy
One of the "relevant principles" is that the description must be adapted.  But that did not happen in the present case: claim 1 was allowed to be amended without any adaptation of the description.  It is not clear why this was permitted.  The UKIPO wrote a letter to ConveTec on 25 October 2011 (which can be seen at IPSUM here) confirming that the amendment was considered allowable, but also stating "However, consequential amendments should be made to the description with the insertion of a statement of invention that is consistent with the wording of the amended claim 1".  This did not happen.

The Court of Appeal has thus relied heavily on statements, such as "that the invention can (and preferably should) be performed with a binding agent concentration between 0.01 and 50%" when -- had correct procedure been followed -- those statements should simply not have been there.

Even if para [0028] was not amended, as it should have been, this Kat finds it most odd that the Court of Appeal should take the view that, when the claim has been narrowed in previous litigation to cure an invalidity problem, statements in the description that support the previous, invalid scope should be relied on to broaden the scope of the amended claim.
Convatec v Smith & Nephew: why the Court of Appeal was wrong Convatec v Smith & Nephew: why the Court of Appeal was wrong Reviewed by Darren Smyth on Wednesday, July 08, 2015 Rating: 5


  1. I disagree that the description was maladapted. The paragraph discloses "In some embodiments, the concentration of agent is between ... of the total volume of treatment." The paragraph does not indicate embodiments of the claimed invention, only embodiments as such, namely embodiments of the whole disclosure of the specification. Reading the indicated paragraph in context of the scope-defining claims, the skilled person would understand that some disclosed embodiments are embodments of the invention as defined by the claims, and others are not. What is significant is that the patent used numerical precision in a certain way, which is wholly consistent with the finding of the judge, and frankly also wholly consistent with conventional technical usage. That said, I can be pretty confident that had a Art 54(3) EPC document existed that disclosed 0.77g, the prosecution attorney would have felt quite comfortable arguing that 1g meant exactly 1g , and not down to 0.5g.

  2. I did not say that the description was maladapted. I said that it was not adapted. Which it wasn't. At all.

    Your argument may be logical, but it is not the EPO principle of adaptation of the description. The Guidelines state "If the claims have been amended, will the description require corresponding amendment to remove serious inconsistency between them? For example, is every embodiment of the invention described still within the scope of one or more claims?" EPO practice is that embodiments are considered to be of the invention unless they are clearly stated to be not so.

  3. "EPO practice is that embodiments are considered to be of the invention unless they are clearly stated to be not so"

    That was certainly the case when examiners bothered. Not any more. Write what you want and claim what you want and the rubber grant stamp will make its mark.

  4. Darren and Anon 2245,
    No. The claims define the invention and the description only helps to explain to the reader. An embodiment not falling within the scope of the claims should either be deleted or identified as not being within the scope (e.g. it is required for completeness of the explanation or shows a feature found in the claims but in a different context) but failure to do so is a lack of clarity which is to be avoided but which does not redefine the claim. It is no more than an error. Thus retaining an embodiment of 40% when the limit is 1-25% does not redefine 1-25 as 40; it does represent an error which should have been avoided as it appears contradictory and not supportive of the claimed subject matter.

  5. Also, remember that under the EPO point-ocracy, the examiner gets points for granting, not for adapting the description... Formally thus, the ISO quality is accomplished, efficiency is king, etc

  6. To Old Man of the EPO
    Indeed, so I am not sure why you begin "no". There is no inconsistency in what I was trying to explain and what you said.

    1. Apologies for the rogue No - chain of thought changed and failure to edit correctly leading to lack of clarity? Oh the irony...

  7. "the skilled person would understand that some disclosed embodiments are embodments of the invention as defined by the claims, and others are not"

    Precisely! The matter is that the EPO knows, and often happens, that national courts will interpret scope under Art. 69 EPC using embodiments outside the scope of the claims as granted.

    This can happen in two ways, both nefarious:
    - as a kind of prosecution history, making those embodiments doubly excluded by the claim. (E.g. the range limit of 1 having 'lower' powers under Art. 69 just because it was originated by an amendment)
    - as a 'forgiveness' of an amendment, clawing back scope that was excised by an amendment (seems to be the present case)

    Might as well remove these embodiments and avoid the temptation to use them.

  8. Old man of EPO - thank you for your last comment. Reading made me laugh more than I can remember for any comment on this blog. Irony indeed. And thank you (no apart) for your lucid explanation of consequential amendment of the description and its perils in the earlier comment.

  9. Maybe I am being incredibly thick, but why can't the number just mean what it says? Should the precision with which one can measure the concentration not merely be an evidential issue when it comes to infringement?

    Perhaps it's the cynic in me, but I can't imagine that the patentee would have been arguing that 1% means 0.5% if there was a prior art disclosure of 0.75%.

  10. Why? Because the Protocol on the Interpretation of Article 69 EPC gets in the way. If someone came along with a 0.99% concentration, should that be excluded also? If the prior art were to disclose 0.75%, there would be most likely good arguments that a claim reciting 1-25% would be lacking in inventive step at the lower end of the range.

  11. Is there any concern that "amending the description" may introduce "new matter?"

    It might not be evident at first glance, but a reduction of words can easily be an enlargement of scope.

  12. Some seem intent on quibbling over the precision of numbers chosen, with a rather "smug" "ha, if there was a prior art X, then surely Y"....

    I do not buy such propositions.

    The point of precision is being ignored with such propositions. Let's not be so easily distracted. There is a range. The range has endpoints. Those endpoints have a designated precision. That precision has a well understood mechanism for demarcation.

    I am just not seeing why this plainly evident matter is being made so complicated by those who do not want to accept how precision is communicated.

  13. With this decision still attracting occasional comments, it is interesting to compare it with the recent decision in T 11/0168, point 4.6 on obviousness where the board stated:

    "With respect to the features of claim 1, the batteries
    of D5 differ only in that the average particle size of
    the FeS2 is not within the claimed range of 1 to 19 μm,
    but slightly lower (average particle size of 0.5 μm)
    (see Figure 2).
    In the board's view, the gap between a battery
    comprising nano-sized pyrite electrodes of D5 and the
    subject-matter of current claim 1 is of an order that
    would not deter the skilled person from bridging it. As
    already said before, an alternative battery having
    essentially the same performance characteristics as in
    D5 could have been expected using a marginally coarser
    FeS2 of 1 μm average particle size."

  14. My reading of the cited paragraphs from the Judgement was that these were used to support a rejection of "Smith & Nephew's favoured interpretation of the claim" i.e. that the range 1 -25 % was exactly 1.00000... to 25.00000... This interpretation of the claim was rejected the earlier judgement by J Birss as well. Therefore, the passage in question does not appear to be significant in the overturning of the original decision.

    However, there does not appear to be any solid reasoning in the judgement why the skilled person should adopt one convention of rounding over another. Both conventions are equally well known, and depending on the number in question, the construed range can vary widely depending on the convention used. Certainly the reasons for finding J Birss in error do no appear convincing.

  15. re Anon at 11:56 - I don't think that "Those endpoints have a designated precision. That precision has a well understood mechanism for demarcation." is a fair characterisation of the situation, since the main dispute as between the first instance and appeal decisions is whether the quoted numbers are to a designated number of decimal places, or a designated number of significant figures. Both acknowledge a precision, but in different terms, and they lead to an opposite outcome on the facts of the case.

  16. Darryn,

    Respectfully, I think that your thinking is not a fair characterization of the point I made.

    Your "but in different terms" is not quite right. I simply have the better point concerning the understanding of precision. You can have any understanding that you want to have. You just cannot have that understanding of your choice and be more precise. I already occupy that position.

    Anon at 11:56

  17. Dear Anon at 11:56

    I am afraid I don't understand your last comment, and perhaps my previous comment needed to be more explicit. So let me set out the possibilities in full.

    Neither Birss J, or Kitchin LJ considered that "1" means "precisely what it says", and does not include, for example, 0.9999. Clearly you don't either, and neither do I, although some commenters seem to be writing in support of that position.

    Birss J judged that "1" should be interpreted to one significant figure. Kitchin LJ believed that it should be interpreted to the nearest whole number. These two interpretations lead to an opposite outcome in the case. They are both "well understood mechanisms for demarcation", which is why I took issue with your original comment - there is not only one such mechanism.

    I consider that the first instance reasons were more cogent than the Court of Appeal decision. If I understand your first and second comments correctly, you believe that the Court of Appeal interpretation is for some reason self-evidently correct. I don't understand why. I don't see at all what is the "better point" that you have, nor why my "in different terms" is "not quite right". Perhaps you could clarify?

    It seemed to me that your first comment was only really an argument against the "means what it says" position, but (rightly in my view) neither judge accepted that, so there is no useful discussion to be had there.

    Best wishes


  18. Anon @ 11:56 has lost me. I have no idea what their position is (exact range, significant figures, +-0.5, or something else). Maybe they do have a better point, but they have not explained what it is yet. Or maybe I missed something?

  19. Darren

    I think there is a perfectly good case for 1 meaning precisely what it says.

    If a claim required a certain part to be 1m wide, clearly it would be ludicrous to interpret this as meaning exactly 1m, such that any difference (nay, if the scale do turn but in the estimation of a hair...) puts the embodiment outside the claim. You would have to interpret it as 1 plus or minus something. But when you are talking about a range there isn't a plus and a minus - there is a single end point of the range, which is either where you said it was or is somewhere else. If you are assuming, say, 5% accuracy, why should 1% - 25% have its lower limit at 0.95 rather than 1.05? And given that there must be a lower limit somewhere, why on earth should it be somewhere other than what has been stated? It can only cause confusion - as here where two courts can't agree on where the value should be moved to.

    Claim construction is based on what the skilled man would think the author was trying to say. It seems ludicrous to have a system for changing it, for example, if they say 1 they really mean 0.5, if they say 0.5 they really mean 0.45, if they say 0.45 etc... I think for a range it should be assumed that what they have said is what they meant, and if that means people can get round it by using values not in that range, then tough.

  20. To the last Anon

    I agree that the argument that the ends of a range should be considered hard limits is credible - I would not be embarrassed to put it forward - although I think that there are some issues around accuracy of determination and reproducibility that will make the endpoints a little fuzzy in many cases anyway. It is not my favoured position, but that is a personal matter.

    The reason why I said that there was no useful discussion to be had is that I am not aware of any court that has taken such a view - neither court in this case, nor the German Federal Supreme Court in, for example, Schneidmesser I, has given a range such a narrow interpretation. So the active discussion is not whether the end points of a range have some flexibility, but how much. You are welcome to disagree with this, but it is where the discussion currently is.

    Best wishes


  21. Not sure I agree with the view that "amending the description to bring it into conformity with the claims" is a relevant principle under the Act. The amendment to section 75 of the Act, which introduced that provision, was brought in to do away with the old "discretionary" approach to amendment in the UK, which isn't (and wasn't) the EPO Approach but had been upheld by the Court of Appeal as still relevant in the UK in Kimberly-Clark/P&G in the late 90s, despite the efforts of Laddie J etc to get rid of it. I don't think the intention of that change to the law was to bring in every aspect of EPO practice on amendment. And I understand that that particular aspect of EPO practice is aimed at minimising interpretation differences across multiple EPC states in which the patent may subsist - here, the amendment was to the UK patent only, so that concern does not arise. The letter from the UKIPO also doesn't go as far as to suggest deleting the paragraph in question, just altering the statement of invention. So I think it is not at all clear that this paragraph should necessarily have been deleted.

  22. Dear Anon

    Thank you for your comment.

    I agree that one purpose of the amendment to s75 was to remove the discretionary approach to amendment in the UK. However, it has done more than that. In Hospira UK Ltd v Genentech Inc [2014] EWHC 3857 (Pat) ( Birss J used it to refuse an amendment to a product-by-process feature because of the EPO's practice of permitting overt product by process claims only if there is no alternative. He said:

    "Moreover in the EPO (relevant as a result of s75(5)), lack of clarity is a ground for refusing an amendment."

    I do not think the paragraph in the description should have been deleted, only amended to remove the unclaimed ranges. The IPO letter is not clearly ordered, but I read the two requirements as being cumulative - to adapt the description and add an appropriate statement of invention. Grammatically it can be read otherwise, but in the context of what is required for a claim amendment, it does not make sense to me any other way. Neither happened of course.

    Best wishes


  23. We see discussions in several jurisdictions, concurrently, that bear on the EPO insistence on "conforming" the description, ever so strictly, to the allowable claims. I think the EPO is to be encouraged to hold to its ultra-strict line. Here's why.

    For UK, see the present discussion.

    For Germany, see Patlit on the Rotorelemente case:

    And for the USA, see also Patlit on the Cuozzo case:

    It is hard enough at the best of times to settle what a duly issued claim means. The EPO approach is for me the only one that gives readers of the B publication a fair chance to get a rough idea what the claim covers, and does not cover.

    Others disagree, I know. But I think they're wrong.

  24. Darren

    Anon of 21:22 here again. I accept that neither court went for the "means what it says" interpretation, but I think it's the most sensible result, so I'll make the case again. It may be extremely optimistic to think that me banging on about it here will get the courts to agree but I can but hope!

    You say that difficulties of measuring make the endpoints a little fuzzy, but the proposed solution does not in my view cure this. If you think that 1 means 1 then anything at about 1 will cause difficulties as to whether it's in or out. If you change it to 0.5 then anything about 1 is clearly in. But anything that is about 0.5 will give you the same difficulties of fuzziness.

    I think the problem is in part historical. In the old days, as I understand it, it was felt unfair to the patentee to give him only what he had asked for - there was a doctrine of "pith and marrow" in which you looked at the claim and decided which features were actually essential to the invention and which the patentee had put in unnecessarily, and the later could be ignored. In the days of Catnic, all the talk of a "variant" is still effectively saying "the claim doesn't actually cover this, but we'll give you protection for it anyway". Kirin Amgen was supposed to put a stop to all that - you read the claims in the light of the description, but once you have worked out what you think the author was asking for, that is all he gets. Indeed, I seem to recall one case since in which the judge said that the courts were "not a branch of social services" (I believe he used those exact words) giving the patentee the monopoly that he could have had but hadn't actually asked for. Nevertheless, there still seems to be ingrained the idea that you must give the patentee a bit more than what he asked for.

  25. Dear Anon of 21:22

    Thank you for your further comment.

    It is unfortunate that you put your preferred position as against the Court of Appeal construction, which I don't think is correct either (see the title of this post). I agree that saying that 1 means 0.5 (the whole numbers/decimal places approach) does not address the accuracy issue and the inherent fuzziness of endpoints that is likely to occur in at least some circumstances. But that is because 1 and 0.5 are both one significant figure, I think. If you adopt the significant figures approach of the first instance decision, then 1 may mean 0.95 but not 0.85 or 0.77. Saying that the claim might cover 0.96 or 0.97, particularly if the figure may be accurate only to within a few percent of the whole (in this case because of the carryover issue, but may happen in other cases because of the inherent accuracy of the measurement) seems to me reasonable.

    I don't agree with you on the historical analysis. There is not room to go into it here, but my understanding is that Kirin-Amgen was saying that the "variant" analysis is part of working out what the claims mean, and that even in Catnic that was so. Maybe I am buying into judicial re-writing of past cases, but I don't believe that an expansive interpretation of a claim under appropriate circumstances is necessarily giving a patentee more than they have asked for. It is working out what the claims really mean, when faced with a concrete example where it is not immediately clear whether it is covered. Pith and marrow is well before my time, I am afraid.

    I don't for one moment think that our discussions here will have the slightest effect on the Supreme Court (if that is where this issue is headed) but I still think it is worth discussing.

    Best wishes


  26. As a relatively neutral non-participant, the outcome of the case if applied to its (il?)logical conclusion would only lead to the following actions, all of which would bring almost all of you down on me like a ton of bricks. Namely:
    1. Should an examiner insist on any numeral being identified as being subject to significant digit rules or others?
    2. Should an examiner object on grounds of novelty to a range of 1-25 when the value in the prior art is 0.77? That has particular Art. 54(3) EPC significance.
    3. Should the examiner allow the applicant to amend this to 1.0-25.0, thereby restricting scope of protection? Would this meet EPC Art 123(2) if only 1-25 had been disclosed?
    4. Would an accidental disclosure of a value of, say, 2% be different from a disclosure of 2.0% with regard to the application of a restriction in terms of a negative feature?

    I can imagine that an examiner would be seen as being pedantic in the extreme, if not unreasonable, to raise any of these points but it seems that s/he should??

  27. It may also be worth considering the real meaning of a patent - the right to exclude others and thus the need to be restrictive on how that right should be interpreted or granted The range of 1-25 was not giving the proprietor the right to that range plus a bit for the purposes of production but was for the purpose of setting a legal restraint on his granted exclusive right. Thus the producer at 0.77 was outside the range but would need to show that his '0.77' did not lead to a distribution around that value which did produce some or too many >1 (normal distribution?). Thus 0.77 could infringe if the control or variation were too great but would not ab initio be infringing based on some interpretation of the meaning of 1.

  28. To Old man of the EPO, off the top of my head:

    1. No - only what is implied by how the number is written
    2. 0.77, no. 0.97 (say) - yes.
    3. No - offends Art 123(2)
    4. Any significant figures approach does not sit happily with EPO practice on disclaiming points in a range, or indeed insisting that "from X to Y" has a different meaning from "between X and Y" for continuous ranges. But the EPO practice is not very easy to defend, since disclaiming an infinitesimal point is highly artificial. I don't have a proposal to resolve this conflict, but the cases of disclaiming an individual value are rare, and I don't see those hard cases as a reason to adopt the "it means what it says" interpretation generally.

    So for what it is worth, there you have it.


  29. 'Darren

    I think there is a perfectly good case for 1 meaning precisely what it says.'

    Without further explanation based on the content of the patent, I am not clear how this view squares with the Protocol on Interpretation, which tells us that a strict literal interpretation should not be used and that a reasonable degree of certainty for third parties and a fair protection for the patentee are the name of the game. That principle is supposed to be applied to all claims and not just those that specify a single value as opposed to a range. Accordingly, it seems to me the name of the game is context and whether a deviation from the literal scope of a claim can still be considered as covered by the claim on the basis it gives a fair degree of protection for the patentee, presumably on the basis the skilled person (third parties) would have expected the claim to cover the variant. I would have thought that in the vast majority of cases patents are not going to be written in such a way that an alleged infringer is going to be able to point to something in the specification that will allow reliance on the argument '1 means 1 and not slightly less' and there is always going to be argument as to where the boundary for slightly less is, which of course bring us back to the problem the courts were trying to resolve here.

  30. 1.0 and 0.5 have the same precision level.

    If that is too confusing, please feel free to use 1.000 and 0.5 (after all, the point of the example is to show a difference in precision).

    Old man of EPO assumes that 1 is rock hard with no precision effect. The reality is the opposite. "1" by itself is the least precise manner of designating a value. This stems from simply understanding number theory (something that most of us was taught in the third or fourth grade - that is not meant as an insult, but rather an objective statement). The "give" has nothing at all to do with production, as patents are by their nature negative rights- not productions rights. Further, a claim to an item just does not care what manner of production (each with it s own capabilities of precision, no doubt) that is used to make the item. That then is easily seen as a logical non sequitur.

    Lastly, as can be seen by this very case (and the fact of the matter that precision does matter) it is not pedantic at all to take what is written by the applicant according to the traditional rules of using numbers. In that sense, a choice between "1" and "1.000" mean two very different things.

    As it should.

  31. Dear US Anon
    I am afraid that if you consider it self-evident that 1.0 and 0.5 have the same precision, then you have not grasped the issue in this case. They are both to one decimal place, true, but 1.0 is 2sf and 0.5 is 1sf, so the best view is that they have very different precision levels.

  32. Yes, you are correct in that you do get to discount the "0" in "0.5" as you do.

    Perhaps you are confusing yourself with the decimal point. As I mentioned, if it helps you and the conversation (I note that you immediately go to a "you don't understand" acrimony - well, so much for "debate," eh?) use 1.000 and 0.5 instead.

  33. Dear US Anon

    Thank you for confirming that 1.0 and 0.5 do not have the same precision level. Now, however, I don't see what your point is. I don't see how it helps me or the conversation to use 1.000 and 0.5 instead. What are you trying to say?


  34. Such an exciting discussion on a case I've unfortunately not yet read, but is on my to-do list. So, I have no opinion one way or another over who is correct. However, if I was drafting a patent claim and I thought 0.5% of a component may be sufficient to work the invention, I would not use a range of 1% to 25% in my claim. Same applies if 0.99999999999999999999% was deemed sufficient.

    In which case, I would not be upset to see a third party use 0.5% (or 0.99etc%) when I had claimed a lower limit of 1%.

  35. Anon of 21:22 here again..

    Darren - I'm not quite sure you followed my point about fuzzy endpoints. To take your preferred construction - if the range is regarded as having a lower limit of 0.95, then 1 is clearly in and 0.5 is clearly out. But anything which is about 0.95 will now be dubious. I don't think you can cure the problem of fuzzy endpoints simply by moving the endpoint elsewhere. So I don't think that that reason is a valid reason for moving the endpoint from what it says.

    To anon of 1:16 - I think in the case of a range there is not a "plus or minus" at each end - the range has to end at one point - and this would mitigate against moving the end points either up or down. And as for giving a fair degree of protection for the patentee, I can't see why giving them just the range they asked for is unfair. The point is that if they are specifying a range, they know that they are intending to claim a range with a lower point and an upper point, with protection for values between these two points and not for values which are below the lower point or above the upper point. If they choose to specify that range by inserting the words "from 1 to 25" into their claim, it seems self-evident to me that they was what they meant. And changing the range arbitrarily to another one scarcely seems to me to give a reasonable degree of certainty to third parties.

    As a further point, I think this case clearly shows the danger of making patent infringement a criminal offence. Can you seriously imagine a situation in which someone is sent to prison because a judge thinks that 0.77 is between 1 and 25?

  36. That last comment encourages me in my feeling that there is something different between a range in a claim and a range in a description. Suppose your invention is a recipe and you want in it a spoonful of sugar. So your recipe says "Sugar, between 0.5 and 1.5 spoonfuls". And if then your competitor uses 0.45 in his rival jam product, has he taken your recipe? Yes, I would say.

    In your professionally written peripheral claim though, you are surely going to claim something like 0.2 to 5 spoonfuls of sugar, just to cover all the possibilities. In a peripheral claim (as opposed to an old-style German "central" claim), you choose your range ends to embrace everything that might conceivably work. If somebody operates outside the claimed range, I think he ought not to be held to infringe. I think that, in general, range ends in claims ought to be construed qualitatively diffferently from range ends in worked Examples.

    All the more reason for the EPO to stay true to its strict line, on conforming the spec to the claims.

  37. To me, the decision seems to be strictly mathematically correct but legally wrong.

    A patent claim shouldn't require a mathematician to be interpreted. The skilled person should be able to interpret a patent claim with a reasonable degree of certainty without the need for recourse to mathematicians or a detailed knowledge of case law. If this decision stands we are now in a position where a claim to a range of "between 10% and 20%" is broader in scope than a claim to a range of "between 6% and 24%": the first defining 5%-25% and the second defining 5.5%-24.5%. This can only make patent law seem ridiculous to the general public.

    To my mind, the decision is legally wrong as it has been made without sufficiently considering what the skilled person reading the claims would understand. In my opinion the court has massively over-analysed what the strict mathematically correct interpretation of the claimed range is without sufficiently taking into account what the skilled person would actually understand when reading the claim.

  38. "And if then your competitor uses 0.45 in his rival jam product, has he taken your recipe? Yes, I would say."

    You say yes. I say no. If he has taken my recipe I have drafted my claim poorly. He is free to make a cake that does not taste as good as mine.

  39. The "mathematical approach" does, in my mind, extend the lower boundary too far. At the upper end of the range, extending to 25.5 provides an additional fuzzy area of 2% of the claimed maximum but at the lower end it is a whopping 50%. This cannot be legally correct.

  40. Dear Anon of 21:22

    Thank you for your comment.

    I think that I have understood your point about fuzzy endpoints – your argument is that moving the end of the range from exactly 1 to 0.95 or 0.5 as the case may be simply shifts the problem of dealing with the fuzziness to a different point. If you are arguing for the “means what it says” construction, it is a good point. I do stand by my previous response to the point, which is that it runs a lot better against 0.5 than 0.95, because 0.5 looks very much like a new endpoint with the same precision as the original endpoint of 1.

    There are a number of further points that I could make in response.

    Firstly, I would argue that using the significant figures approach is not moving the endpoint, it is determining what “1” means. “Exactly 1” effectively means 1.000000 (carry on for as many zeros as you wish) so that 0.9999999 (ditto) does not fall within it. I don’t think that approach is ever used in technical, scientific or mathematical discourse.

    Secondly, and in response to your “cure” point, I don’t think that the significant figures approach cures the problem of inherent fuzziness in the sense of makes the problem entirely go away. I don’t think that you can make the problem go away. But it does acknowledge the problem, and to some degree address it. If for example a parameter can only be determined to an accuracy and precision of a few percent of the value, then a reported value of 1.01 might well correspond to a true value of 0.98. Or a reported value of 0.97 might well correspond to a true value of 1.00. It seems to me that in such a situation saying that 1 means 1.0000000 is simply not meaningful or realistic. The significant figures approach is the scientific and mathematical way of acknowledging this reality. I appreciate that you may respond that a reported value of 0.97 might well correspond to a true value of 0.94, so that the true value is actually outside the claim scope – I acknowledge that and I don’t think that there is a perfect solution or cure. But I still see the significant figures approach as better.

    Thirdly, against the “means what it says” interpretation, as Anon of Tuesday, 14 July 2015 at 01:16:00 says, I don’t think it squares with the Protocol on Interpretation.

    And finally (and to disagree here with Anon of Wednesday, 15 July 2015 at 09:13:00) the claims have to be interpreted by the notional skilled person. I don’t see how you can hold that the skilled person would interpret 1 as 1.00000000000 because that is never done, not only in mathematics (strictly) but in any scientific or technical discipline. To repeat part of my first point, I don’t consider it a matter of moving the endpoint, rather as determining what “1” means.

    I don’t have any particular axe to grind here, and I know no more of the case than is in the two judgments, but having considered them both I do think both Courts were correct to dismiss the “means what it says” approach.

    Best wishes


  41. To Anon at 10.00 today

    Sorry your comment did not appear until after I posted my comment at 10.21. Your argument stands against the Court of Appeal decision, but the first instance decision had a to my mind better mathematical approach where the lower limit was 0.95, providing similar fuzziness at both ends of the range. The "whole numbers" approach is actually not very mathematical, and significant figures are more technically meaningful, which is why I think the first instance decision was better than that of the Court of Appeal.

    Best wishes


  42. There is apparent confusion about "moving" an endpoint and what an endpoint - in and of itself - means.

    ALL numbers serving as a target - be that number one ended (an edge of a range) or two ended (no range) have the usual rules of rounding applied to them. It is a logical fallacy to then attempt to round the rounded part.

    MaxDrei notes a key distinction that is added to the basic treatment of the number itself: the relation of the claim to the invention. But I am not sure that the view of strict fence (outer limit) or center pole (this is the general idea with some penumbra) is exactly helpful here. In both types of claims one still has to take an understanding of what the numbers mean and in both types, the agnostic rounding simply is as it is - the claim style does not matter. The "cover all possibilities" option provided does not cover all possibilities (there is still a range and that range still has ends, and those ends are numbers which still have to be understood as capable of being rounded).

    This is NOT so much as "needing a mathematician" as simply understanding that a mathematician merely describes what is. The skilled person already knows this - the skilled person is a construct (not a real person) that knows ALL pertinent art. It is a legal mistake to think that this must comport with "public perception" because the public is the wrong legal notion to use.

    I would add that the idea of using a percentage based rounding is interesting but the relative aspect artificially treats large numbers differently than small. A system that treats the rounding agnostic to the relative size of the target number that the rounding is being applied to is in line with the art. If the writer of the claim wants a different rounding aspect, then that is when the choice between 1.0 and 1.0000 comes in. Remember, choosing does matter. 1.0 and 1.0000 are not the same number in the legal sense. Or the mathematical one.

  43. To the US Anon

    The skilled person does not know ALL art:

    "the person skilled in the art should be presumed to be an experienced practitioner who has average knowledge and abilities and is aware of what was common general knowledge in the RELEVANT art concerned at a particular time".

    I contend that the skilled person reading this patent would never expect 1% to be rounded down to 0.5% as that is not what is conventionally done in the relevant art.


  44. [I'm not sure if that went in or not - I'll try again - feel free to delete if this comes out twice.]

    Hi Darren (Anon of 21:22 again)

    Thanks for your further comment. It may be the mathematician in me, but I don't think I can accept that you are not moving the endpoint. If you have a range (ie it doesn't have gaps, and it doesn't go on forever) and that range includes everything from 1 to 25 and also includes some values below 1, then it will still have an endpoint. Look up "greatest lower bound" for details. I can accept if you say that this is a range whose lowest point is "what they mean by 1" - this gets us back to familar territory - but I don't think you can deny that there is an endpoint, nor that the endpoint is at a value that isn't actually 1.

    You mention the protocol on interpretation, but I can't see why "means what it says" is not the right interpretation. If seems fair both to the patentee - they get what they asked for - and fair and clear to third parties - they can go up to the boundaries, ie anywhere the patentee didn't ask for.

    Perhaps if I listed some of my assumptions you could say where you start to disagree?
    The patentee draws up a claim to specify, with precision, what the scope of his invention is, ie what other people cannot make or sell.
    He knows when he writes the claim that this is what it is for.
    He knows he wants to specify a range; he is only seeking protection for some values and is happy (for whatever reason) not to claim protection for values that are too high or too low, for some definition of "too high" and "too low".
    He knows he is putting values in his claim in order to do this.

    If you swallow all this, why do you then think the values he has written are not actually what he wants?

  45. Dear Anon of 21:22 again

    Thank you for your further comment.

    I don't think the endpoint has moved (I do agree that there is an endpoint) - there is only one end to the range, and it is where it is on the correct construction of the claim. the question is where is it?

    I think where we part company is simply this. I think you agree that if the patentee writes "1" in isolation, he can be understood to mean it with the stated degree of precision - one significant figure. But you consider that if he uses it at the end of a range, it no longer means that, but 1.0000000 recurring. I think it still means to one significant figure.

    So the values he has written are the ones that he wants, but he wrote "1", not 1.000000 recurring.

    I think that is all that stands between us.

    Best wishes


  46. To summarise: a range of, say, 0.90 to 2.20 is a narrower range than 1 to 2?

  47. Not sure if this is a summary...

    Is a range of

    0.90 to 2.20

    narrower than a range of

    0.90000 to 2.20000

    To me, it's pretty obvious there is a real difference and that the second range is appreciably narrower than the first. And I am no mathematician.

  48. This discussion of precision is all very well, but did not both the High Court and the Court of Appeal fail to appreciate the potential significance of the WORDS (as opposed to the numbers) used to define the range?

    I had always thought that there was a difference in meaning between the following alternatives.

    (a) "between 1 and 25"
    (b) "from 1 to 25"

    That is, the range specified in alternative (b) clearly encompasses the termini (i.e. 1 and 25), whereas alternative (a) does not.

    Does this analysis not mean that "between 1 and 25" actually EXCLUDES 1.00000 (and any other number that is not BETWEEN that and 25.00000)? Or are we really to accept that the patent claim is to be read as meaning alternative (b), even though it is phrased very differently?

    And what about the range "greater than 1 but less than 25". To me, that ought to be interpreted as having an identical scope to (a), i.e. excluding the termini. However, given the interpretation afforded to (a) by the Court of Appeal should we also interpret that range as meaning any number from 0.50 to 25.49 (or greater than 0.50 but less than 25.49)?

    The point here is that surely the wording chosen by the patentee to define the range ought to have an influence on the interpretation of that range - as there are clearly instances where the meaning conveyed by the words overrides any considerations of numerical precision.

  49. Finally read the judgement. I must say I prefer the final decision, mainly because it is a less convoluted way of determining what a number means. Rounding up has always been the method of choice for physical scientists. When measuring out my arsenic and strychnine samples, I never used the significant figures method.

    The thought that 0.5% should infringe 1% is, on the face of it, nonsensical. However, looking at the problem objectively, precision must be considered.

    Having said all that, as a patent attorney I would be perfectly happy with a decision that says 1 means 1.00000000. If 0.999999999% of a feature (strychnine) was sufficient to perform a task (I shall not incriminate myself here), I would expect to cover substantially non-working values below this amount in my claim. For example: 0.5%. From an infringement point of view, the drafter should have done a better job and should not expect the client to rely on arguments over the appropriate method for determining precision.

  50. The Cat that Walks by HimselfSaturday 7 November 2015 at 18:52:00 GMT

    What is the end of this story? Has Smith & Nephew managed to bring the case before the Supreme Court. I hope so. A beautiful law can come out of the case, with bright perspectives for Smith & Nephew.

    @ Darren,

    Paragraph [0028] can stay in the description of the amended patent. It does not really matter whether it is in or not, I would say.


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