As was rightly noted on this blog, the skilled person’s “hope” of solving the objective technical problem using the means that led to the (later claimed) invention, has disappeared from the Guidelines for Examination. What we are left with is the (perhaps) more objective “expectation of some improvement or advantage (see T/83)”. Interestingly, this expectation of “some improvement or advantage” no longer appears to be so closely linked to the objective technical problem than the language previously used in the Guidelines. Whether this will in the future give rise to more problems for applicants or patentees remains to be seen. In any case, it may be a good point in time to remind ourselves that even recognizing a problem and its roots can (at least sometimes) be an invention of itself.

Art. 52(1) EPC reads:

“European patents shall be granted for any inventions, in all fields of technology, provided that they are new, involve an inventive step and are susceptible of industrial application.”

As is laconically stated in the Case Law Book, 9th Edition:

The application of Art. 52(1) EPC presents a problem of construction as there was no legal or commonly accepted definition of the term “invention” at the time of conclusion of the Convention in 1973. Moreover, the EPO has not developed any such explicit definition since. Art. 52(2) EPC is merely a negative, non-exhaustive list of what should not be regarded as an invention within the meaning of Art. 52(1) EPC.

Nonetheless, there may perhaps be the perception that an invention is to be defined as the (more or less ingenious) solution to a particular problem. The EPO’s Problem and Solution Approach may be conducive to such an understanding. According to the Guidelines for Examination, this approach essentially consists of the following steps:
(a) identifying the “closest prior art”,
(b) assessing the technical results (or effects) achieved by the claimed invention when compared with the “closest state of the art” established,
(c) defining the technical problem to be solved as the object of the invention to achieve these results, and
(d) examining whether or not a skilled person, having regard to the state of the art within the meaning of Art. 54(2) EPC, would have suggested the claimed technical features in order to obtain the results achieved by the claimed invention.

From this, you would perhaps think that the “technical problem to be solved” (the objective technical problem) is a more or less artificial construct that is objectively derived from the results or effects achieved by the invention when compared with the closest state of the art. Inventive step only comes in the last step (d) where it is examined whether the skilled person would have suggested the claimed solution in order to solve the objective problem.

However, as the decision T 2321/15 by the Technical Board of Appeal 3.3.07 shows, such an understanding would be too narrow. In certain cases, the invention may also reside in recognizing a particular problem, whereas the subsequent solution thereof may appear relatively trivial.

Facts of the Case

European Patent No. 2 034 951 related to a method for formulating storage stable and easily rehydratable dried pharmaceutical compositions, which are used as chemo-embolic compositions.

Claim 1 of the main request read as follows:

A method for formulating a dried product suitable for direct administration to an animal as an embolic agent after rehydration to form a suspension comprising:
(i) a freezing step in which particles of polymer matrix swollen with water and having absorbed therein a non-volatile biologically active compound are cooled to a temperature below the freezing point for water;
(ii) a lyophilisation step in which the cooled particles from step (i) are subjected to a reduced pressure at which ice sublimes for a period during which at least a portion of the absorbed ice sublimes and water vapour is removed; and
(iii) a packaging step in which the dried particles are packaged;

characterised in that the packaging step is carried out under reduced pressure and the package containing the particles is substantially airtight and has an interior under vacuum; and the particles are substantially spherical in shape and the particle sizes are selected such that upon rehydration in 0.9wt% saline at room temperature, the average particle size is in the range 40 to 2000 micrometers.

The opposition division revoked the patent on the ground of lack of inventive step. D4 disclosed the preparation of PVA porous microspheres comprising an active agent for embolization, by a method involving a freeze-drying step, and was taken as the closest prior art. The OD came to the conclusion that the sole difference in view of D4 was that the sealing process was carried out under vacuum, and considered sealing under vacuum obvious, since it was commonly known that residual air in lyophilized microspheres inhibited the rehydration process, and it was an obvious measure to overcome this problem by applying a vacuum, which was also known from D11 and D17.

Recognition of an unknown problem

The patent proprietor filed an appeal against this decision, arguing that the problem to be solved by the contested patent was the improvement of the rehydration of the particles and the resolution of the buoyancy problem, which was due to the presence of air pockets in the particles.

The Board agreed that it was not known before that air penetrated the pores of the particles and caused a high buoyancy when rehydrated. The invention was thus found to reside in the recognition of this unknown problem linked with said air pockets in the particles.

The Board further considered that it was true that rehydration of a vacuum stored product was generally known, but not in relation to the problem of the present invention concerning embolic particles. As D4 did not mention the presence of air pockets in the porous microspheres and any of the associated problems, starting from D4 the skilled person would not have been motivated to change the process to perform the sealing process under vacuum conditions, i.e. the question asked was would (not could) the skilled man have added a sealing and storage step under vacuum.

Consequently, the Board agreed with the appellant that the problem posed by the contested patent is an unrecognized problem in D4 and acknowledged inventive step on this basis.


Decision T 2321/15 thus came to the interesting conclusion that the discovery of a yet unrecognized problem may give rise to patentable subject-matter in spite of the fact that the claimed solution may be, once the root of a problem has been identified, retrospectively trivial and in itself obvious. As such, T 2321/15 is not the first decision of its kind, but rather follows a long tradition starting with T 2/83 itself, which was confirmed in T 764/12. It may thus be prudent for parties applying the problem-solution-approach to include the recognizability of the objective problem and its cause into their considerations.


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  1. Some litigators aver that the EPO’s Problem-Solution Approach is OK, as far as it goes, for Patent Offices, but not flexible enough for courts trying the validity of issued patents. One of the criticisms that has been made (and then “gone viral”) is that EPO-PSA cannot cope with “problem inventions” (those in which it took inventive insight to state the problem).

    One really ought to wonder, what are the motives for litigators so determinedly to do down EPO-PSA. Does the brutally clinical and clean PSA enquiry, for example, restrict their abilities to bill more hours of time spent by their attorneys and subsidiary “fee-earner” helpers, whenever the obviousness issue is in play. Or is it that litigators can rake in more, whenever the obviousness enquiry proceeds differently, in every different EPC country (unlike issues such as novelty and added matter, where the established case law of the EPO more or less holds sway all over Europe). Litigators love uncertainty, their customers less so.

    Whatever. Meanwhile, thank you Thorsten and colleagues, for shooting this canard, this invented “problem invention” problem with EPO-PSA.

    One more thought: The criticism that formulation of an “Objective Technical Problem” is “artificial” is also misconceived. As the Boards have recently reminded us, the notional addressee of a patent, the “person skilled in the art” is about as “artificial” as can be, so why shouldn’t the problem ascribed to such a construct also be “artificial”. More important is that i) the test be objective, and NOT subjective, and ii) the test should be not only simple and fair but also readily perceivable to be simple and fair by those caught up in, and financing the patent system, that is to say, inventors, patent owners, those accused of infringement, and all those technical experts called upon to give evidence in revocation proceedings. On that hangs the public acceptance of the patent system.

  2. To be honest, such decisions occur once in a blue moon, and not too much weight should be given to them.

    I would rather consider that problem inventions is the kind of justification given quite often by representatives when none of their arguments in respect of inventive step have been accepted by a division.

    Let’s put it this way, try it, let’s scrape the barrel, but do not be surprised that in the vast majority of cases it fails.

    In spite of this rather sniggering comment I wish Thorsten Bausch and all its crew a Happy New Year, with a lot of case law to comment!

  3. This decision is welcome. However, a case can be made for a broader challenge, not of the problem-solution approach itself, but of its systematic use by the EPO.
    This approach is strong but as any tool, its validity is not universal. Its structured reasoning sequence works quite well when there is a clear, undisputable closest state of the art, and it provides an efficient safeguard against hindsight-guided reasoning, likely to occur when the examiner has broad discretion in assembling state of the art items. There is typically an undisputable closest state of the art when an invention relates to an improvement to an existing technique.
    But there are far from infrequent cases for which it is unsuitable, beyond the category of “problem inventions” recognised in decision T 2321/15. A first type of situation occurs when there is no undisputable closest state of the art (e.g. there is no close state of the art relating to the same field of use as the claimed subject matter) and different lines of reasoning exist depending on the state of art selected as the closest. This entails specific difficulties. Another type of situation occurs in the pharma field when as a result of systematic screening it has been discovered that a certain molecule possesses a therapeutical effect. There may be in such cases no logical reasoning for linking the structure to the effect and discussing whether the effect could have been expected.

  4. The problem-solution-approach (PSA) is no more than a tool, and like any tool it can also have some drawbacks. One of the often stated drawbacks is the choice of the closest prior art. But this is an artificial one. Nowadays most inventions have a starting point as they mainly represent incremental advances in technique.

    That the inventor is meant to be aware of everything which has been made available to the public before filing is as much a fiction as the person skilled in the art. No reason to despair with the PSA.

    Interestingly in a parallel blog the discussion turns about the choice of the closest prior art:

    I fully agree with Max Drei and is comments about litigators. Imagine the UPC comes, and it will not adopt the PSA. What a way for all those litigators to fill their pockets!

    If lack of inventive step is to be shown, it suffices to show than one way of using the PSA leads to a lack of inventive step for the claim not to be patentable.

    If it comes to show the presence of inventive step, it might become useful to have another try if there is a document which can also be considered as closest prior art. If the result is also positive, then one can consider that the claim indeed shows the required inventive step.

    There are very rare cases in which there can be really different true closest prior art documents. One example is T 591/04. In the latter case, both ways lead to a lack of inventive step.

    The problem-solution-approach is a development of case law. It started in chemistry and diffused slowly in the other technical areas, whereby the mechanical boards were the most reluctant. Nowadays you will barely find a decision of the Boards of Appeal not using the PSA, and in some decisions you have also a discussion why one document is better than another one as closest prior art. Why do you think that by not using (or using it wrongly) the PSA a candidate to the EQE will earn a ticket for the following year?

    There might be some rare cases when the PSA cannot be used, but the number of real pioneer inventions is so low nowadays that they should not weigh much when it comes to the acceptance or not of the PSA. In such a situation, I think for instance to the invention of the bipolar transistor or the modern photocopy (originally called Xerography as invented by Rank-Xerox), one can forget the fact that the PSA does not really work. But then doubts about inventive step are misplaced.

    I am however not sure that systematic screening can be considered as leading to inventive step. This is routine work which in my humble opinion has nothing inventive in it. Everybody doing this kind of routine work can expect to obtain some results, but are those then a proof of inventive step? It is more a question of means available than of true inventorship.

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