Identifying the problem without hindsight (T 0605/20)

Hindsight is the pernicious and ever present enemy of patentees. However one may strive for objectivity in inventive step analysis, it can be difficult to overcome the inevitable prejudice that comes with being told the solution to a problem ("it just seems so obvious now you say it!"). In the recent decision T 0605/20, the Board of Appeal considered the risks posed by hindsight in inventive step analysis where part of the invention is identification of the problem to be solved. Whilst the Board of Appeal admitted that hindsight is necessarily needed to identify the closest prior art, they warned against allowing hindsight to influence the objective assessment of obviousness in view of the closest prior art. 

Legal Background: Hindsight and determining the closest prior art

Inventive step at the EPO is assessed by the problem-solution approach. First, the difference between the prior art and the claimed invention is identified. Second the technical contribution of this difference is determined, and in particular what problem it purports to solve. The question then becomes whether the solution represented by the technical contribution would have been obvious to a skilled person in view of the closest prior art. 

Hindsight is always 20:20

A critical aspect of the problem solution approach is the identification of the closest prior art, according to which the inventive contribution of the claimed invention can be assessed (Case Law of the Boards of Appeal, I-D-3.1). Over the years, Boards of Appeal have established a number of ways by which the closest prior art may be identified. Under one approach, the closest prior art is the document pertaining to the most relevant purpose that has the most structural features in common. In such an analysis, the similarity of purpose between the prior art and the claimed invention is to be given more weight than the number of features the prior art and claimed invention have in common. The closest prior art should also be the prior art document that provides the most promising starting point for an obviousness attack. 

However, the step of identification of the closest prior art in the problem solution approach creates a potential tension with one of the most fundamental aspects of inventive step analysis: the avoidance of hindsight. This tension exists because knowledge of the invention and the problem it purports to solve is necessary for identifying the closest prior art, as confirmed by the Board of Appeal in T 1087/15 (r. 1.1.3):

"knowledge of the claimed invention is [...] absolutely necessary in order to formulate the objective technical problem, irrespective of how 'close' the prior art document is to the claimed invention; the features differentiating the claimed subject-matter from the starting document must be identified, their technical effect determined and thus the problem to be solved formulated."

Correct inventive step analysis must therefore ensure that the hindsight necessarily used to identify the closest prior art to a claimed invention does not leach into the subsequent problem-solution analysis. Awareness of this risk is critical in cases where the technical contribution of an invention resides in the identification of the objective technical problem to be solved in view of the closest prior art. The problem to be solved in view of the closest prior art may only have become obvious with hindsight. It is therefore critical that the way in which the objective technical problem is formulated does not unfairly point towards the claimed solution (T 800/95). As such, formulation of the objective technical problem to be solved in view of the closest prior art must be distinct from the process of identifying the closest prior art. 

Avoiding hindsight for a invention based on identification of the problem

The patent in question (EP1687019) related to a formulation of  therapeutic peptide (liraglutide). Claim 1 as granted specified a pharmaceutical formulation comprising the therapeutic peptide and propylene glycol. At Opposition, the patent was maintained as granted. 

On appeal, the Opponents argued inter alia that the claims lacked inventive step. The difference between the subject matter specified by claim 1 and the prior art was identified as the use of propylene glycol instead of mannitol as an isotonic agent. The specification contained data from a clogging test showing that the use of propylene glycol, in contrast to mannitol, prevented the formation of unwanted deposits that would impede administration of the formulation through a syringe. Whilst the closest prior art (WO 03/002136) also described tests for formulation stability, these did not test the formulations in a clogging test. The prior art thus did not look for or report on the formation of deposits. 

The Opponent argued that the use of the prior art formulations would inevitably lead a skilled person to recognise that these formulations had an instability problem leading to the formation of undesirable deposits. The Opponent further argued that it would be obvious to a skilled person that mannitol or glycerol were the culprits, and that these should be replaced with propylene glycol in order to solve the problem. 

The Board of Appeal did not agree with the Opponent. For the Board of Appeal, there was a lack of any indication in the prior art that the formulations could or should be tested for their propensity to form deposits. As such, for the Board of Appeal, the undesired phenomena forming the basis of the objective technical problem to be solved by the claimed invention would not have been inevitably manifest upon the practical implementation of the teaching of the prior art (r. 4.2.3). Recognition of the problem to be solved was therefore identified as part of the inventive contribution of the claim. The Board of Appeal therefore dismissed the Opponent's obviousness attack for being based on hindsight.

Final thoughts

This latest decision from the Boards of Appeal follows a similar train of analysis as that of T 1349/19 which also rejected an obvious attack for being based on hindsight (IPKat). Both cases were also related to pharmaceutical formulations. Formulation IP has traditionally fared less well against obviousness attacks, falling down under attacks citing a clear incentive to innovate in the field of successful therapeutic. The decisions of the Boards of Appeal in T 1349/19 and T 0605/20 are a reminder that the problem-solution approach should focus on the closest prior and resist any tendency to hindsight based on knowledge of a drug's success in the clinic or otherwise. 

Further reading

EPO Board of Appeal dismisses step-by-step inventive step attack for being based on hindsight and cherry-picking (T 1349/19)

How do you protect patents from judicial and expert hindsight?

Identifying the problem without hindsight (T 0605/20) Identifying the problem without hindsight (T 0605/20) Reviewed by Rose Hughes on Friday, January 20, 2023 Rating: 5


  1. Perhaps the problem to be solved could be formulated as 'providing an improved composition', i.e. without reciting what the improvement actually is.

    1. The unqualified concept of “improvement” does not belong in an OBT as it is inherently subjective.

  2. Another decision disregarding the long-standing line of case law (the recognition of a technical problem should only exceptionally contribute to inventiveness). Here, monitoring stability of a protein solution in terms of clogging is the first thing that a skilled practitioner would routinely do. Which has nothing to do with hindsight.

  3. In the USA, the old "TSM" (teaching, motivation, suggestion) obviousness enquiry continues to attract adverse comment, and this spills over into criticism of the EPO's TSM enquiry (called the problem-solution approach) by people who do not understand EPO-PSA or have limited or poor experience of how it works.

    An accurate comparison of the two approaches by somebody who understands both would be instructive. Whereas the American approach descends into arm-waving subjectivity, a properly conducted inter Partes debate to determine the correct OTP (objective technical problem) will BOTH eliminate ex post facto pollution of the obviousness enquiry AND render it truly objective.

    I would wish that more people explain persuasively, to patent practitioners remote from Munich,
    these vital positive attributes of EPO-PSA.

  4. I would also add MaxDrei that in my recent experience EPO opposition divisions do not understand PSA very well. They define the problem in terms of the new science being contributed rather than the contribution over the closest prior art, and so an incorrect framework is set up to identify the nature of the leap made from the closest prior art. This is especially true if the contribution over the closest prior art includes the nature of the data that supports the solution which needs a very sophisticated analysis of how reasonable expectation of success is impacting how the skilled person would proceed

  5. It is of note in this decision that while the Board finds that the problem is not known, they
    continue with business as usual, i.e. apply the PSA. Logically, if the problem is not known, the PSA should be held inapplicable. But apparently this is impossible, the BOA is bound to define an objective problem, even it is general to the point of being meaningless. After all, this is established case law. The PSA has become a signature feature of EPO case law and practice, a part of its identity.

    Overall the PSA is indeed an efficient tool to avoid hindsight. As acknowledged in the Guidelines, hindsight is inevitable for prior art search, since there is no way for a search to be carried out without the knowledge of the invention. With this in mind, avoiding hindsight in the assessment of inventive step is crucial albeit challenging. But as any tool, the PSA has its limits, such as the case of a « problem invention » as in the decision. Such cases are perhaps infrequent but not exceptional, I recently audited a case in which the applicant/representative had not identified the novelty of the problem (the PSA is so deeply ingrained in the EQE training) and struggled to get the patent granted.

    Inventions consisting of a new use of a product is esp. challenging for the PSA. The case law and the Guidelines make clear that the closest prior art must have the same purpose or use as the claimed invention, this trumps similarity of structural features. The relevant « problem » is thus linked to the field of use. This suggests that the usual presentation of the PSA as a three-step methodology lacks a critical preliminary step, which is the definition of the « art » of the skilled person.

    1. Instant reactions, Mr Hagel. 1) I don't see any difficulty with a "problem invention" under EPO-PSA. As you say, it is up to the petitioner/Applicant/inventor to assert that the perception of the problem counts was part (at least) of the inventor's inventive activity. 2) EPO-PSA gives (or should give) Applicant full faith and credit for their choice of i) technical field and ii) subjective problem addressed by the real inventor. So I'm not following you, why initial determination of the "art" in which the inventor was active is lacking, when the EPO runs its PSA obviousness enquiry. It's the "art" that Applicant decrees, in the application as filed, isn't it?

  6. Dear MaxDrei,

    You are absolutely right, it is up to the applicant to assert the technical field and the problem they seek to adress in their application. This was pointed out inter alia in G 1/19 on simulation. I need to add that the "technical field" should not be defined so broadly as to encompass every conceivable field of use. For example (this is personal experience), if a claim as worded is for a capacitor in general, without specifying it is intended for use in a high voltage distribution network, this makes no sense, because the problems are entirely different from the problems for low voltage capacitors.
    That being said, my remark had only to do with the way the PSA is usually presented, not with the practice of the EPO, which I approve as I said in my comment.


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