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Plausibility and non-working embodiments

30th Aug 2018

In our previous articles, “Where’s your supporting data? Plausibility at the EPO” and “You’ll have to do better than that! An update on plausibility at the EPO”, we considered the increasing significance of plausibility at the EPO, particularly when assessing inventive step and sufficiency.

In this article, we consider whether the EPO may be taking this concept too far, and its potential conflict with another area of established EPO case law.

Plausibility and claim scope

The often-cited AgrEvo case (T0939/92) is considered to be the case which introduced the concept of plausibility into EPO law and practice. AgrEvo concerned a product claim for a class of chemical compounds for use as herbicides. On appeal, the Board of Appeal held that the patent was invalid for obviousness. The invention was found to reside in the finding that the compounds have herbicidal properties. However, the Board held the following:

“However… this technical problem could only be taken into account if it could be accepted as having been solved, i.e. if, in deciding the issue under Article 56 EPC, it would be credible that substantially all claimed compounds possessed this activity…”

The Board held that the technical effect must not be ‘inherently unlikely’ in substantially all the compounds. Instead, it must be ‘reasonably predictable’, ‘fairly assumed’ or ‘credible’. The Board was not satisfied that substantially all compounds claimed were likely to be herbicidally active.

Its adoption into EPO practice is reflected in the EPO Guidelines for Examination (G-VII, 5.2), where it is stated that a technical problem may be regarded as being solved only if it is credible that substantially all claimed embodiments exhibit the technical effects upon which the invention is based.

If a strict approach is taken to the assessment of plausibility, particularly with respect to the requirement that substantially all embodiments falling within the scope of the claim should solve the technical problem, one can envisage how this could undermine established drafting and prosecution strategies.

Take, for example, the following hypothetical situation. An inventor discovers a novel compound (compound X). They find that it is effective in treating disease Y when administered at 1 g, 4 times per day, by oral administration in the form of encapsulated liquid tablets. Established EPO practice suggests that the inventor would be entitled a claim directed to compound X for use in the treatment of disease Y. However, if one were to apply the plausibility requirements strictly, it could be argued that the claim encompasses a large number of embodiments which would not reasonably be expected to work and hence the problem (of treating disease Y) would not be solved across the scope of the claim. For instance, the claim encompasses administration of very low amounts of compound X (much lower than those exemplified) that are unlikely to be high enough to be effective, and very high amounts of compound X that may be harmful to the subject. Also the claim encompasses modes of administration (e.g. topical) and formulations (e.g. ointments) that are unlikely to be effective.

Similarly, if the inventor had claimed “a pharmaceutical composition comprising compound X and a pharmaceutically acceptable excipient or diluent”, one could argue that the presence of the open “comprising” language (which is typically interpreted as “including”) would mean that the claim could encompass any number of other components in addition to compound X and the excipient or diluent. Any number of possible hypothetical components could be included which could undermine the action of compound X and would mean that the invention would not work. For example, it would encompass a composition having compound X and cyanide (which would not be expected to treat disease Y because its administration would kill the subject).This hypothetical scenario may seem rather absurd but it is not unheard of for opponents to advance similar types of arguments during opposition proceedings before the EPO.

Could a strict application of the plausibility case law spell the end of Markush structures in pharmaceutical patents? Markush structures are frequently included in claims because they are a simplified way of covering a group of chemical compounds with related structural features. Typically such structures encompass hundreds or thousands (or even millions) of hypothetical compounds. Could it reasonably be expected that substantially all compounds encompassed by the Markush formula could treat a particular disease, particularly when the patent typically only specifically exemplifies a handful of such compounds?

Indeed, if one considers the vast majority of patent claims, in any technical field, it is possible to conceive embodiments falling within the scope of the claim that would be unlikely to work.

Non-working embodiments

There exists a strand of EPO case law which concerns the effect of non-working embodiments encompassed by a claim and which could be considered to be at odds with the plausibility case law.

Enlarged Board of Appeal decision G1/03, which primarily concerned undisclosed disclaimers, held the following.

 “If a claim comprises non-working embodiments, this may have different consequences… Either there is a large number of conceivable alternatives and the specification contains sufficient information on the relevant criteria for finding appropriate alternatives over the claimed range with reasonable effort. If this is the case, the inclusion of non-working embodiments is of no harm…

 If this is not the case and there is lack of reproducibility of the claimed invention, this may become relevant under the requirements of inventive step or sufficiency of disclosure. If an effect is expressed in a claim, there is lack of sufficient disclosure. Otherwise, ie if the effect is not expressed in a claim but is part of the problem to be solved, there is a problem of inventive step…”

 Other Board of Appeal decisions have considered this issue. T 14/83 held that it was not decisive that the claim encompassed non-working embodiments:

“…in the event that such a teaching cannot be defined in a claim precisely enough to rule out occasional lack of success, such a claim is not to be objected to provided it is possible to deduce from the description the action to be taken – which also cannot be precisely defined – by way of fine tuning the variables”. “…occasional lack of success of a claimed process does not impair its feasibility … if, e.g., some experimentation is still to be done to transform the failure into success provided that such experimentation is not undue and does not require inventive activity”.

The Guidelines for Examination (F-III, 5.1), with reference to G1/03 explains:

“In some particular cases (for example claims relating to a combination of ranges or Markush claims), the scope of the claim might encompass a large number of alternatives, some of which correspond to non-working embodiments. In such cases, the presence of non-working embodiments in the claim is of no harm, provided that the specification contains sufficient information on the relevant criteria to identify the working embodiments within the claimed alternatives (G 1/03).”

Although T 14/83 refers to “occasional lack of success”, G 1/03, does not appear to put a limit on how many non-working embodiments may be encompassed by a claim, provided the specification contains sufficient information on the relevant criteria for finding appropriate alternatives over the claimed range with reasonable effort.

A happy medium?

In the author’s opinion, the application of the plausibility case law, particularly the apparent requirement that substantially all embodiments falling within the scope of the claim exhibit the technical effect, should not be interpreted in a rigid fashion, and the scope of the claim should be considered with the skilled person in mind, to avoid potentially absurd situations and provide fair reward for the patentee. Could the case law concerning non-working embodiments provide an effective counterbalance?

One may consider the hypothetical example of a patent with a claim directed to an adhesive composition X, comprising:

1-10% of A

1-10% of B; and

1-10% of C

In the specific examples of the patent, there is exemplified the following hypothetical compositions which all show improved adhesion compared to prior art compositions, resulting from a synergistic effect between components A, B and C.

1% A; 10% B; 10% C

10% A; 1% B; 10% C

10% A; 10%B; 1% C

There is no example showing improved adhesion where the composition comprises 1% A, 1% B and 1% C; or 2% A, 2% B and 2% C, etc. and perhaps there may be some doubt over whether such small amounts of each component would lead to improved adhesion.

If the claim is interpreted in a strict sense with respect to the plausibility case law, then this claim would lack inventive step on the basis that it is not plausible that the technical effect is realised across the scope of the claim, i.e. that substantially all embodiments encompassed by the claim show improved adhesion. However, even if one were to accept that the embodiments in which each of A, B and C were present in small amounts did not provide an improved adhesion over the prior art compositions, then the case law concerning non-working embodiments would appear to provide the necessary balance. The skilled person, given the teaching in the patent, could easily adjust the amount of components A, B and C, with reasonable effort, to identify the working embodiments within the claimed alternatives.

Although plausibility is a hot topic at the EPO, the case law is still very much in development. However, if you are faced with an objection from the EPO during examination for lack of plausibility, or if an opponent raises this issue during opposition proceedings, it is worth considering the case law concerning non-working embodiments.

This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.

Andrew Carridge
About the author

Would you like to know more? You can talk to Andrew Carridge who will be able to help. Call +44 (0)1223 360 350


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