Classes, subclasses and post-grant amendments before the EPO
Narrowing a chemical class of compounds to a subclass or a specific compound can be a legitimate strategy for defending a patent. However, where the claim in suit also defines the class in quantitative terms, such amendments may give rise to objections under Article 123(3) EPC. Resolving these issues requires particular care, especially given that the case law on the matter is not uniform.
Firstly, let’s look at the scenario below, which illustrates why such amendments, though seemingly limiting, can inadvertently extend the scope of protection.
Claim 1 as granted, directly corresponding to claim 1 as originally filed, defines a composition comprising several components, including a hydrocarbon:
1. A composition comprising […]; and from 1 to 10% by weight of a hydrocarbon.
During opposition proceedings, the patentee wants to file auxiliary requests defining the hydrocarbon component in more detail. The patentee files auxiliary requests 1 and 2 (AR1 and AR2) with claim 1 amended as shown below, directly based on the disclosure in the description of the application as filed:
1. A composition comprising […]; and from 1 to 10% by weight of an unsaturated hydrocarbon (AR1)
1. A composition comprising […]; and from 1 to 10% by weight of a hydrocarbon isoprene (AR2)
The amendments look simple at first glance. There is, however, a problem under Article 123(3) EPC. Post-grant amendments cannot extend the scope of protection of the patent as granted, but the proposed amendments do just that, even though they clearly limit the scope of the class of compounds of granted claim 1 (hydrocarbons). So, what’s going on?
Claim 1 as granted limits the content of ‘hydrocarbons’ (i.e. any hydrocarbons, be it unsaturated or saturated) to from 1 to 10% by weight.
Thus, an exemplary composition including 8% by weight of butane (a saturated hydrocarbon) and 6% by weight of isoprene (an unsaturated hydrocarbon) is not covered by claim 1 as granted, as the total content of 8+6=14% by weight of those hydrocarbons does not fall within the range of ‘from 1 to 10% by weight’.
Meanwhile, claim 1 of AR1 refers to from 1 to 10% by weight of unsaturated hydrocarbons. The claim does not refer (explicitly or implicitly) to the content of saturated hydrocarbons. The amendment in claim 1 of AR1 has thus removed the implicit limitation on the content of saturated hydrocarbons that was present in claim 1 as granted.
If we were dealing with a claim defining compositions “consisting of” the stated components, the above would not raise any eyebrows. However, claim 1 is drafted using the “comprising” language, meaning that the claimed compositions can include other components in addition to those recited in the claim.
Thus, our exemplary composition comprising 8% by weight of butane and 6% by weight of isoprene, not covered by claim 1 as granted, is now covered by claim 1 of AR1 – the content of isoprene, an unsaturated hydrocarbon, falls squarely within the range of from 1 to 10% by weight, while the concentration of butane or other saturated hydrocarbons is not limited at all.
The requirements of Article 123(3) EPC are thus not met, as the amendment in claim 1 of AR1 extends the scope of protection beyond that of the claims as granted.
There is a similar problem with claim 1 of AR2, of course – our exemplary composition falls within the scope of that claim, as only the content of isoprene is limited (with 6% by weight falling within the range of from 1 to 10% by weight) but the claim allows for the presence of 8% by weight of hexane due to the “comprising” language.
Note that this problem also arises in cases where the claim includes a list of species (“from 1 to 10% by weight of X, Y and/or Z”) and one or more of those species are deleted.
Let’s consider the possible ways out of this conundrum by looking at the case law in the field.
T 2017/07 (Board 3.3.10)
Unfortunately, there was no happy end for the patentee in T 2017/07, but it is worth a mention as many decisions on this topic refer to that decision.
Claim 1 as granted was directed to a composition comprising several components and included a feature: “an alkylene carbonate having 3-5 carbon atoms […], wherein the content of the alkylene carbonate having 3-5 carbon atoms is 0.5-50% by weight”.
Claim 1 before the Board further included the phrase “the alkylene carbonate being propylene carbonate” (3 carbon atoms).
Claim 1 was found not to comply with Article 123(3) EPC. The Board considered that the required weight content in claim 1 at issue applied only to propylene carbonate, whereas, in claim 1 as granted, it applied to the entire class of alkylene carbonates having 3-5 carbon atoms. This meant that e.g. granted claim 1 did not cover compositions comprising 30% butylene carbonate (4 carbon atoms) and 30% propylene carbonate (i.e. 60% by weight of alkylene carbonate having 3-5 carbon atoms), but such compositions were covered by amended claim 1.
The patentee argued that the wording of claim 1 excluded the presence of any other alkylene carbonates having 3 to 5 carbon atoms. However, the Board said that such interpretation was arbitrary; it would require giving two different meanings to the term “alkylene carbonate having 3 to 5 carbon atoms” – narrower for the chemical structure and broader for the weight content.
For the Board in T 2017/07, there was thus no real difference between “feature A, wherein the content of A is x%, said A being B” and “x% of B”.
Note that the patentee’s rescue attempts (which, in all fairness, were reasonable: “propylene carbonate being the sole alkylene carbonate”; compositions “consisting of” the stated components) fell on Article 123(2) EPC…!
T 999/10 (Board 3.3.09)
Claim 1 before the Board included a feature of from 45 to 85% by weight one or more styrenic block copolymers (claim 1 as granted) and, following an amendment, further included the phrase “wherein the styrenic block copolymer is a SIS type copolymer”.
According to T 999/10, this sequential or ‘cascading’ language (e.g. weight content + [the broader feature] ‘and in which/wherein [the broader] is [the narrower]’) solves the problem of extension of scope of protection and avoids the situation envisaged in T 2017/07; the Board said that such wording “leaves no doubt as to the owner's intention to exclude from the scope of protection sought all other block copolymers other than those of the SIS type. In particular:
“A reader familiar with the formulations used in the patent claims therefore infers from the amended claim that only SIS-like copolymers may now be present in the adhesive among the block copolymers described”
However, the Board also commented on an alternative interpretation of the claim, wherein the originally imposed weight content still applies to the entire class, but the claim does not exclude the presence of other block copolymers. In that case, the claim amended using the sequential/cascade wording would cover (i) from 45 to 85% by weight one or more styrenic block copolymers and (ii) from 45 to 85% by weight one or more SIS copolymers. Thus, the total content of the class cannot exceed 85% by weight, but SIS must be present in an amount of from 45 to 85% by weight.
Similar approach was also followed in a number of later decisions, e.g. in T 2215/18 (Board 3.3.07); the claim referred to a composition comprising an alkylcellulose in a content of between 1 and 60% by weight, “with said alkylcellulose being ethylcellulose”. According to the Board, it was clear from this wording that no other alkylcellulose than ethylcellulose could be included in the composition, and the requirements of Article 123(3) EPC were met.
Likewise, in T 1063/15 (Board 3.3.07) and T 1935/22 (Board 3.3.06), an amended claim introducing the clause “wherein [the broader] is [the narrower]” and retaining the weight percentage + [the broader] clause was held to comply with Article 123(3) EPC. The Boards considered that the wording restricted the class to specific components and excluded the presence of further components of that class.
That said, there are quite a few decisions that criticise the reasoning in T 999/10.
T 287/11 (Board 3.3.10)
In (frequently cited) T 287/11, the Board rejected the approach in T 999/10 as being based on a subjective criterion - the Board said that the intention of the proprietor was irrelevant to interpreting the scope of protection.
Claim 1 before the Board specified the presence of from 5-90% by weight of a class of compounds (the feature was present in granted claim 1); the problem was that the amended claim also required that the class conforms to a given chemical formula.
The Board interpreted the amended claim as requiring the stated weight content to apply only to compounds of the given chemical formula, thus allowing the presence of other members of the broad class in an undefined amount.
The patentee saved themselves by including an additional feature requiring that the total content of the class (no reference to the chemical formula) be 5-90%.
Thus, the amended claim required the presence of 5-90% by weight of the class; and further required the presence of 5-90% by weight of compounds of the specific formula belonging to the class.
Perhaps the claim could have also been worded as: 5-90% by weight of ‘a class of compounds’, wherein the class comprises compounds of a given chemical formula.
This, of course, is different from a claim requiring the presence of 5-90% by weight of compounds of a specific formula belonging to a class, to the exclusion of other elements of that class (as in e.g. T 999/10).
T 1360/11 (Board 3.3.07)
In a similar way, T 1360/11 teaches that our problem “may be avoided by including in the amended claim a quantitative condition on the limited class or list of compounds and an additional constraint on the total amount of compounds belonging to the broader class or list”.
Thus, the claim that was found to be allowable under Article 123(3) EPC in T 1360/11 included:
(i) the limitation of granted claim 1, i.e. from 0.001 to 10% of a metal ion source (defined in terms of classes of compounds as “zinc salts, copper salts, silver salts, nickel salts, cadmium salts […]”; and
(ii) the limitation of claim 5, i.e. from 0.01 to 5% of a metal ion source selected from specific zinc and copper compounds (“zinc oxide, zinc carbonate […] copper thiocyanate”)
Feature (i) is the “additional constraint on the total amount of compounds belonging to the broader class or list”, while feature (ii) is the “quantitative condition on the limited class or list of compounds”.
T 514/14 (Board 3.3.06)
In T 514/14, claim 1 as granted referred to “0.25 to 5% of a phosphate builder salt”, while claim 1 before the Board referred to “0.25 to 5% of a phosphate builder salt which is sodium tripolyphosphate”.
The patentee argued that the claim formulated in this way meant that the total relative amount of any or all phosphate builder salts present had to be within the range from 0.25% to 5%, and that all of the phosphate builder salt present was in the form of sodium tripolyphosphate.
The Board said that the claim lacked clarity due to ambiguity in the wording “allowing for two substantially different interpretations of the claim”, and also that it extended the scope of protection. One interpretation was the patentee’s interpretation; the other one was that the weight content limitation applied only to sodium tripolyphosphate.
Those issues could not be resolved by amending the claim to specify “[…] phosphate builder salt, wherein the phosphate builder salt is sodium tripolyphosphate”
The Board relied on T 287/11 in its reasoning on extension of scope of protection.
T 664/20 (Board 3.3.10)
This fairly recent decision criticises T 999/10 whilst siding with the more rigorous approach of T 287/11.
The catchphrase of the decision states, amongst other things, that the cascade/sequential wording is likely to lead to an ambiguity and that such wording cannot be used to interpret the claim in the same way as in T 999/10.
Claim 1 as granted defined an adhesive composition comprising at least one functional comonomer and included the phrase “characterized in that […] the functional comonomer is composed of at least one reactive function in the form of an acid, anhydride or epoxide group, the level of which is less than 1% by weight of the composition”.
One of the auxiliary requests expanded this phrase to insert the wording “said functional comonomer being maleic anhydride”. The patentee argued that the request was formulated in line with the principles of T 999/10 and hence was allowable under Article 123(3) EPC.
However, the Board noted that a number of decisions (including T 287/11 and T 514/14) did not follow this approach. In particular, the Board noted that T 287/11 taught that the intention of the drafter was irrelevant to interpreting claim scope; it also endorsed the comments in T 514/14, according to which an amendment should not lead to an ambiguity, especially if the amended claim can be reasonably interpreted as extending the scope of protection.
Thus, the Board found that the claim at issue did not meet the requirements of Article 123(3) EPC based on the reasoning akin to that in T 287/11; the limitation on the weight content was held to apply only to maleic anhydride itself.
The patentee solved the problem by (i) specifying earlier in the claim that “the functional comonomer is maleic anhydride” and (ii) amending the above phrase to “the content of functional comonomer […] is less than 1% by weight of the composition”.
Again, this claim was interpreted as requiring the presence of maleic anhydride, with the weight content of the class (to which maleic anhydride belonged) being limited to less than 1% by weight; i.e. other members of the class could too be present in the composition, to the extent that the weight content limitation was satisfied. In this regard, it is worth mentioning the following comment from the Board:
“if [the appellant‘s] real intention had been to exclude all functional copolymers other than maleic anhydride from the composition for the claimed use, this should have been clearly and unambiguously expressed in the claim by stating that the only functional copolymer present in the composition is maleic anhydride, provided of course that this feature has support in the application as filed (Article 123(2) EPC)”
T 170/22 (Board 3.3.04)
Another fairly recent decision; it refers to the line of case law including T 664/20 but does not follow its approach, instead accepting the cascade wording similar to that in T 999/10 (although this particular decision was not discussed by the Board).
Claim 1 as granted referred to a composition comprising between 1 % and 10% by weight of a binder. Claim 1 before the Board further included the phrase “wherein the binder in the composition is selected from polyvinylpyrrolidone, methylcellulose, hydroxypropyl cellulose and hydroxypropyl methylcellulose”.
The Board interpreted this wording as imposing two separate conditions on the binder in the claimed compositions: it must have been present in an amount of between 1 and 10% by weight and it must have been one of polyvinylpyrrolidone, methylcellulose, hydroxypropyl cellulose and hydroxypropyl methylcellulose. In other words, the claim required the presence of between 1-10% by weight of the listed binders to the exclusion of all other binders. According to the Board:
“The use of in-cascade-drafting in an open claim ("comprising"), namely retaining in an amended claim the broad definition of the claim as granted and adding, by means of the phrase "and wherein...", an additional restriction, avoids the situation where an amendment initially made with the intention of restricting a claim actually extends the protection conferred by it”
The opponent argued that the exclusion of the presence of other binders was not derivable from the application as filed (Article 123(2) EPC).
The Board acknowledged that the application as filed did not explicitly disclose that binders other than the four binders listed in claim 1 could not be present in the claimed composition. However, the Board considered that the qualitative limitation of the binder in amended claim 1 (“wherein the binder is […] hydroxypropyl methylcellulose”) inherently had the effect of excluding binders other than those listed in amended claim 1.
Interestingly, T 170/22 says that T 664/20, T 514/14 and T 2017/07 would not apply on the present case on the basis that the wording of the relevant claims was allegedly different. I am not sure I entirely agree with this reasoning…
T 1551/23 (Board 3.3.02)
The decision was published earlier this month. Claim 1 as granted defined compositions including a polyglyceryl fatty acid ester surfactant and a phosphate ester co-surfactant in a particular weight ratio. Claim 1 as amended specified that the co-surfactant was “potassium cetyl phosphate”.
The opponent raised an objection under Article 123(3) EPC. The patentee argued that the cascade-like language alone led to a double limitation not extending the scope of protection.
Based on the text of the decision, the patentee tried to support its position by relying on numerous decisions in the field; the problem perhaps was that in some of those decisions the cascade formulation was found to be allowable (e.g. T 999/10), while in the other ones it was expressly rejected (e.g. T 287/11).
The Board disagreed with the patentee, noting that the idea that the cascade definition alone automatically led to a double limitation and to a claim not extending the scope of protection was not in accordance with the prevailing view in the case law.
The decision comes with a plot twist, as claim 1 before the Board was a verbatim combination of granted claims in the context of the co-surfactant being “potassium cetyl phosphate”.
Thus, the Board said that claim 1 could not extend the scope of protection beyond that of the granted claims: “Whatever is protected (or not) by the amended patent was already protected (or not) by the patent in its granted form”. The Board emphasised that in T 287/11 and T 2017/07, amendments were based on the disclosure in the description, rather than on the combination of the granted claims.
Nevertheless, seems like this Board had little sentiment towards cascade/sequential formulations.
T 2447/18 (Board 3.3.06)
This decision is worth noting, as the patentee’s attempt to introduce a double limitation (as in e.g. T 1360/11) was found to violate Article 123(2) (!) EPC.
The claim at issue contained the following feature (text in bold shows additions compared to the claim as granted):
“from 0.002% to 0.4%, by weight of the total composition, of a non-ionic antimicrobial active, which is not a perfume component, wherein the composition comprises 0.002% to 0.4% of 4,4' dichloro-2-hydroxy diphenyl ether”
The ether compound (diclosan) is a ‘non-ionic antimicrobial active’ (which is not a perfume component).
The Board said claim 1 as amended encompassed compositions which may comprise either diclosan as the sole non-ionic microbicide (in the given weight content) or 0.002-0.4% of a mixture of non-ionic microbicides with diclosan, wherein diclosan was present in an amount of at least 0.002%.
In the case at hand, the Board considered that there was no basis in the application as filed for either of those compositions; the amendment added subject matter beyond the content of the application as filed.
Despite the lack of reasoning on Article 123(2) EPC, it does seem that the Board was happy with a claim request wherein diclosan was the sole antimicrobial active.
Interestingly, T 287/11 gets a mention in the present decision. According to the Board, in T 287/11, there was no investigation as to whether “mixtures of polyalkylene glycols [class] containing an amount of polyalkylene glycols of the defined formula [member of the class] corresponding to the lower limit of the claimed concentration range were directly and unambiguously disclosed in the application as filed” (!).
Conclusions
For those finding themselves needing to amend claims along the lines discussed in this article, it is important to be aware that there appear to be two lines of case law in this area: one requiring a double condition, the other settling for a cascade-type formulation. While there are some decisions that accept cascade/sequential wording, I would tread lightly…!
Any viable way out of the conundrum must, of course, have a clear basis in the application as originally filed (see e.g. the comment from the Board in T 664/20), and T 2447/18 shows that basis for such amendments may not always be accepted. Claim scope can hinge on subtleties, and it is thus important to draft composition per se applications with those considerations in mind.
Similarly, carefully crafted fallbacks can prove helpful, e.g. the wording “consisting of”, “consisting essentially of”, or “wherein the composition does not comprise any further [elements of the class] other than those specified in the claim” can help escape the problematic situation, especially if the wording is present in the granted claims. Of course, such fallbacks can be quite limiting, so should always be drafted with commercial relevance in mind.
Finally, the case law suggests that patentees stand a better chance of fending off objections of this type if they rely on features taken from the granted claims; amendments based on the description are more exposed to objections under Article 123(3) EPC and may even be scrutinised for compliance with Article 84 EPC.
If you have any questions about EPO practice, feel free to get in touch.
This article is for general information only and is not intended to constitute legal advice. If you would like tailored advice on a specific matter, please do not hesitate to contact me.
