Co-authored by Rachel Bateman of D Young & Co and Simon Klopschinski of Rospatt, this article was first published in GRUR Patent 8/2025, published 21 August 2025. Republished here with kind permission of GRUR Patent.

I Introduction

Very often the validity of a European patent is decided in the context of inventive step. Therefore, inventive step pursuant to Article 56 of the European Patent Convention (EPC) is one of the most important requirements for patentability in proceedings at the European Patent Office (EPO) as well as in litigation before domestic courts across Europe [1]. The concept of inventive step is not, however, uniformly assessed; there are some differences between the practice of the EPO, on the one hand, and the case law of the domestic courts, on the other hand, in the application of Article 56 EPC [2].

One of the premises of the Unified Patent Court (UPC) is to provide a single, centralized court for handling infringement and validity disputes of both European patents with unitary effect and European patents. Since the entering into force of the Agreement on a Unified Patent Court (UPCA) on June 1, 2023 it has therefore been eagerly awaited how the UPC will evaluate the question of inventive step. One of the first rulings in this respect was the decision rendered by the Paris Central Division (Paris CD) on November 5, 2024 in the revocation action between the Claimant NJOY Netherlands and the patentee and Defendant Juul Labs International regarding European patent EP 3 504 991 B1 (patent at issue), which is titled “Vaporization Device Systems”.

NJOY Netherlands and Juul Labs International are both producers of e-cigarettes. The invention claimed by the patent at issue is directed to improvements in electronic vaping devices. The Paris CD divided claim 1 of the patent at issue into the following features:

1. A cartridge suitable to be used in a device for generating an inhalable aerosol with an airflow path, the cartridge having
2. a fluid storage compartment (32);
3. a channel (50) comprising a portion of an air inlet passage (51);
4. a second air passage (41) in fluid communication with the channel, the second air passage (41) being formed through material of the cartridge;
5. a heater (36) affixed to a first end of the cartridge, the heater comprising a heater chamber (37) in fluid communication with the second air passage;
6. a first condensation chamber (45) in fluid communication with the heater chamber;
7. a second condensation chamber (46) in fluid communication with the first condensation chamber;
8. a mouthpiece (37) affixed to a second end of the cartridge wherein said mouthpiece comprises an aerosol outlet (47) in fluid communication with the second condensation chamber; 1.9. the air inlet passage (51) is formed by assembly of a device body and the cartridge.

According to the Claimant the invention claimed by the patent at issue was not new and did not involve an inventive step. In its decision of November 5, 2024, the Paris CD dismissed the revocation action as unfounded [3]. The decision was appealed by the unsuccessful Claimant. In the meantime, the appeal has been withdrawn and the proceedings have been closed [4]. The question therefore remains open as to what position the Court of Appeal of the UPC would have taken in this case.

In the parallel opposition proceedings before the EPO, the Opposition Division revoked the patent at issue for non-compliance with Article 123(2) EPC. The decision of the Opposition Division is currently under appeal as T 1926/23 and following a Communication from the Board dated January 22, 2025, proceedings have been accelerated pursuant to Article 10(5) RPBA in view of the parallel proceedings before the UPC. Oral Proceedings before the Board have been scheduled for October 10, 2025.

In the following the first instance decision of the Paris CD is analysed from the perspective of EPO practice (see item II. below), German law (see item III. below), and the case law of the UK courts (see item IV. below). Even though the grounds for the decision overlap with all of the aforementioned legal systems, the Paris CD's considerations reveal a preference for the German approach when assessing inventive step. The conclusion of the present analysis is that the UPC should strive for an interpretation of the EPC which is coordinated with both, the case law of the domestic courts and EPO practice (see item V. below).

II European Patent Office

The approach of the EPO to the assessment of inventive step under Article 56 EPC has been under heightened scrutiny since the issuance of UPC decisions addressing inventive step. In particular, there has been a lot of discussion on the robustness of the “problem- solution approach” as defined e. g. in the EPO Guidelines for Examination5, and whether patent owners need to be concerned that whilst a European patent may be granted following this approach to inventive step by the EPO, it may be at risk of being found invalid due to a lack of inventive step during any subsequent UPC proceedings because an approach to inventive step not strictly based on “problem- solution” is currently being adopted by at least some UPC first instance divisions [6].

1. Determination of the closest prior art

The first step of the EPO’s “problem-solution approach” is the determination of the “closest prior art”. There is no statutory obligation on the EPO to formally construe the claims prior to the assessment of the closest prior art, although in practice such interpretation is conducted by the divisions of the EPO simultaneously with the consideration of potentially relevant documents for novelty and/or inventive step. Following the recent Enlarged Board of Appeal decision of G 1/24 [7], such interpretation is to be from the claims as the starting point with the description and drawings consulted when assessing the patentability of an invention under Articles 52 to 57 EPC and not only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation. In their decision, the Enlarged Board highlighted that the diverging case law of the Technical Boards of Appeal of the EPO was contrary to the practice of the UPC [8], whereas their conclusions were consistent with the Order of the Court of Appeal of the UPC in NanoString Technologies v 10xGenomics of February, 26 2024 [9]. It remains to be seen how G 1/24 will be implemented by the EPO’s divisions and Technical Boards of Appeal.

In the present case, the Paris CD were faced with a single starting point for the assessment of inventive step (US 2011/0036346 A1; referred to as “Cohen”) and the Claimant sought to argue that the claimed invention of claim 1 did not involve an inventive step because it was obvious to the skilled person in view of Cohen combined with common general knowledge or US 8,333,197 B2 (referred to as “Cross”).

With a single starting point, it was not necessary for the Paris CD to comment on whether a determination of the “closest” prior art was required but they still did so. In particular, they emphasised that reference to “state of the art” in Article 56 EPC is objective meaning that “an invention shall be considered as involving an inventive step if, having regard to any element that forms part of the state of the art, it is not obvious to a person skilled in the art” [10]. They also noted that “Limiting the evaluation of inventive step to certain elements of the prior art, for example a document perceived to be ‘the closest prior art’, generally bears the risk of introducing subjective elements into the evaluation, for example if the reasons for disregarding certain elements of the prior art are of subjective nature” [11].

Whilst the EPO’s approach to inventive step is intended to be objective, indeed the second stage of the problem-solution approach is the definition of an “objective technical problem”, the deliberate use of “any element” by the Paris CD and their comments on risking the introduction of subjectivity is notable. It highlights a clear difference between the first stage applied routinely by at least the EPO Examining and Opposition Divisions (the Appeal Boards can be known to take a more holistic approach) to inventive step and the assessment being taken in this case.

Another potential difference vis-à-vis EPO proceedings is the ability of the court to introduce issues of its own motion. The Claimant did not present inventive step objections starting from either of the documents cited for novelty and the Paris CD noted that it is the “Claimant that defines the scope of evaluation for a revocation action. The Court does not evaluate reasons for revocation that the Claimant has not raised” [12]. This is in contrast to inter partes proceedings before the EPO where some Boards (and even opposition divisions) have been known to introduce issues of their own motion.

Article 114(1) EPC stipulates that the EPO “shall not be restricted” in their examination of the facts in proceedings “to the facts, evidence and arguments provided by the parties”. In inter partes proceedings, Article 114(1) EPC thus gives the opposition divisions and the appeal boards the discretion to examine the validity of an impugned patent beyond the facts, evidence and arguments presented by the parties, and this discretion can be utilised. In T 1370/15, for example, the board introduced an inventive step objection for the first time in their preliminary opinion which was based on its own common general knowledge arising from its own technical expertise in the field, and ultimately decided that the patent in question was invalid for lack of inventive step [13].

2. Formulation of the objective technical problem

The second stage of the EPO’s problem-solution approach is the definition of the objective technical problem.

According to the EPO Guidelines for Examination, this is the establishment “in an objective way” of “the technical problem to be solved”; the “aim and task of modifying or adapting the closest prior art to provide the technical effects that the invention provides over the closest prior art”. The reference point for the definition of the objective technical problem is the closest prior art and the distinguishing feature(s) of the claimed invention [14]. Such an approach was not applied by the Paris CD.

Instead of defining an “objective technical problem”, the Paris CD considered the “underlying problem” of the patent-in-suit in order to determine whether the difference with Cohen (“the starting point”) was obvious [15]. The difference between the claimed invention and Cohen was notably not involved in the definition of the problem.

As the patent at issue did not formulate a specific underlying problem, the Paris CD took it upon themselves to arrive at an underlying problem based on their interpretation of the claim [16]. This is comparable with how the EPO arrives at the closest prior art, and overlaps to some extent with the definition of the technical effect when formulating the “objective technical problem” insofar as the effect is not explicitly stated in the description. In T 2255/10, for instance, the board with reference to T 482/92 stated that in establishing the closest prior art, the question to be asked was, what, in the light of the application as whole, would be achieved by the invention as claimed [17]. In G 2/21, the Enlarged Board of Appeal stipulated that a patent applicant/proprietor may rely upon a technical effect for inventive step if the skilled person, having the common general knowledge in mind, and based on the application as originally filed, would derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention [18].

In summary, whilst the Paris CD did not define an “objective technical problem” in the same manner that patent owners are familiar with from examination before the EPO, there seems to be some similarities as to how a technical advantage was defined and considered for the assessment of inventive step. In particular, there was an assessment of the problem that is solved by the claimed subject-matter, and this was not limited to the claim language but considered the claim in view of the application as a whole. The “underlying problem” to be solved also did not require an explicit statement of a technical effect in the patent at issue, but was derived from the interpretation of the claims, i. e., aligned with being “encompassed by the technical teaching and embodied by the same originally disclosed invention”.

3. Considering whether the skilled person would have arrived at the claimed solution

The final stage of the EPO’s problem-solution approach is to answer the question of whether the skilled person, starting from the closest prior art and the objective technical problem, would have arrived at the claimed solution. This is often quoted as the “could-would” approach; the point is not whether the skilled person could have arrived at the invention but whether they would have done so because the prior art provided motivation to do so. The Paris CD adopted a similar approach but from the “underlying problem” not the “objective technical problem”.

Firstly, the Paris CD identified an interrelation between the heater and mouthpiece in the language of claim 1 and concluded that the underlying problem of the claimed subject-matter was “to optimize the parameters of the inhalable aerosol that is inhaled by the user”. This problem was then used to assess whether the skilled person would be motivated to arrive at the claimed invention [19].

The Paris CD focussed on the term “activity” in each of the French and German versions of Article 56 EPC and explained how “An activity can be motivated by an underlying problem”. Rather than defining a problem vis-à-vis the closest prior art for the distinguishing feature(s) (as is the approach of the EPO), the Paris CD thus defined an underlying problem visà- vis the specification for the invention as a whole, and used this problem to assess the motivation of the skilled person [20].

The difference between the claimed invention and Cohen was the position of the heater chamber; the heater chamber in Cohen was not “affixed to a first end of the cartridge” [21]. In their assessment of whether the skilled person would have “found” the invention from Cohen, the Paris CD commented on the underlying problem and reasoned that since there was no suggestion in the state of the art to affix a heater, which comprises a heater chamber, to a first end of the cartridge (in the sense of the claim), the invention did not follow from the prior art in such a way that the skilled person would have found it in his attempt to solve the underlying problem [22]. This was despite the optimisation of such parameters being “an intrinsic motivation in the field of devices for generating an inhalable aerosol” given that the aerosol is the product that the device is to produce [23]. Hence, the patent at issue was found to be inventive.

Overall, it seems likely that the EPO would have reached the same conclusion using the problem-solution approach in the absence of a relevant teaching in the art. The issue of inventive step was not, however, discussed in the parallel opposition proceedings since the Opposition Division revoked the patent at issue for non-compliance with Article 123(2) EPC. It remains to be seen how the Board will approach inventive step in the pending appeal proceedings, and to what extent, reference will be made to this decision of the Paris CD.

III. Germany

Against the background of the coming of the UPC a number of articles recently published in legal journals authored by judges and practitioners, discuss the differences in the assessment of inventive step undertaken by the EPO, on the one hand, and German courts, on the other hand [24]. Engels and Ackermann clearly criticize the EPO’s handling of inventive step, in particular the concept of “closest prior art”, and speak out in favour of the German way of evaluating inventive step as the approach less prone to hindsight [25]. Deichfuß, by contrast, sees the differences as being less pronounced and acknowledges that the outcomes of the respective examinations are often similar [26]. In view of the – depending on the eye of the beholder – more or less clear differences between the practice of the EPO and the German courts, the question arises as to which path the UPC will take when examining inventive step [27]. In the present case, although the reasons for the decision partly overlap with the EPO's practice (see item II. above), the Paris CD's considerations in assessing inventive step reveal a certain preference for the German approach, as the following explanations show.

Prior to assessing whether the invention claimed by the patent at issue actually involved an inventive step, the Paris CD clarified that the evaluation of inventive step is an objective approach [28]. The court based this understanding on the concept of the person skilled in the art which ensures that, for instance, subjective consideration of the inventor do not influence the evaluation of inventive step [29]. Another aspect of the objective approach, according to the Paris CD, is the reference to the state of the art in Article 56 EPC which according to Article 54(2) EPC shall be held to comprise everything made available to the public by means of a written or oral description, by use, or in any other way, before the date of filing or the earliest priority date of the European patent application [30]. These explanations of the Paris CD are in line with EPO practice and German case law which both hold that inventive step is an objective requirement of patentability that refers to the person skilled in the art whereas the subjective perception of the inventor or applicant, including its ignorance of the state of the art, is irrelevant [31].

1. Claim construction and formulating the technical problem

As a first step of evaluating the patentability of the patent at issue, the Paris CD delved into an extensive interpretation of the claims and, in doing so, defined the technical problem underlying the claimed invention [32]. Since the patent specification did not articulate a technical problem, the Paris CD relied on claim 1 of the patent, namely the relationship of features 1.5 and 1.8 as well as features 1.6 and 1.7, in order to conclude that an underlying problem of the claimed invention was to optimize the parameters of the inhalable aerosol that is inhaled by the user [33]. The Paris CD not only relied on the features of the claim to determine the technical problem, though, but also referred to a prior art document called “Cross” which the court regarded as a confirmation of its understanding of the underlying problem [34].

The findings of the Paris CD fit in well with the practice of German courts that, unlike the EPO, do not define the technical problem on the basis of a comparison of the claimed invention with a specific prior art document, that is the so-called “closest prior art” [35]. Instead, formulating the technical problem is part of the construction of the claim, which precedes the assessment of patentability [36]. The UPC and German courts agree that the same standards of claim construction should apply to both, infringement and patentability [37].

In the case decided by the Paris CD the applicant had not included any explanations regarding the underlying technical problem into the patent specification [38]. German courts may regard such a “subjective technical problem” as an indication of how the person skilled in the art understands the claim. This practice of German courts is, however, subject to the general principles of claim construction which prescribe that the claim takes precedence over the description. Therefore, only the objective technical problem is relevant in the end, which German courts determine on the basis of the individual features of the claim in their context [39]. The Paris CD followed this approach when it found on the basis of the relationship of the features of the claim that an underlying problem of the claimed invention is to optimize the parameters of the inhalable aerosol that is inhaled by the user [40].

Since German patent law does not employ the concept of “closest prior art”, the German notion of technical problem, different from the EPO, does not mean the aim and task of modifying or adapting the closest prior art to provide the technical effect that the invention provides over the closest prior art [41]. The purpose of defining the technical problem under German patent law is rather finding the starting point from which the person skilled in the art endeavours to enrich the prior art without knowing the invention beforehand [42]. The CD Paris seems to have a similar understanding when they explain that “It is then decisive, whether what is claimed as an invention did or did not follow from the prior art in such a way that the skilled person would have found it in his attempt to solve the underlying problem on the basis of its knowledge and skills, for example by obvious modifications of what was already known” [43].

In the EPO opposition proceedings regarding the patent at issue an opponent had argued that the objective technical problem was the provision of an air passage [44]. Since an air passage is an element of the claimed invention, this approach carries the risk that the formulation of the technical problem predetermines the assessment of obviousness. Therefore, in line with the EPO practice, German courts require that the technical problem is defined as abstract and neutral as possible[45]. In cases of doubt the technical problem should be defined even more abstract [46]. The Paris CD followed suit by avoiding elements of the claimed invention in its definition of the underlying technical problem, that is optimizing the parameters of the inhalable aerosol that is inhaled by the user.

The formulation of the technical problem and the subsequent question of whether the solution to the technical problem is obvious vis-à-vis the prior art are – from the perspective of German law – separate issues [47]. Therefore, German courts regard possible incentives in the prior art or the question of whether the claimed invention is suitable to solve the underlying technical problem as irrelevant when developing the technical problem in the first place [48]. The reference of the Paris CD to the prior art document called “Cross” and the discussion of motivations the person skilled in art might derive from this document in the context of developing the technical problem, seems to be not fully aligned with the German practice [49].

Since the Paris CD only developed one technical problem, that is optimizing the parameters of the inhalable aerosol that is inhaled by the user, the case law of the Technical Boards of Appeal of the EPO and German courts according to which a claimed invention may have several underlying technical problems each of which requires an individual assessment, was not relevant in the case at issue [50].

2. Finding a starting point

Even though only one prior art document was considered as starting point by the Paris CD in its evaluation of inventive step under Article 56 EPC, the Paris CD apparently regarded it as necessary to make a general statement that limiting the evaluation of inventive step to certain elements of the prior art, for example a document perceived to be “the closest prior art”, generally bears the risk of introducing subjective elements into the evaluation, for example if the reasons for disregarding certain elements of the prior art are of a subjective nature. However, the Paris CD supplemented these remarks with the note that for reasons of procedural efficiency it may be justified in a particular case to focus the debate on a certain element or on certain elements of the prior art and it may be justified in a particular case to reduce the evaluation of other elements of the prior art to a minimum [51].

The Paris CD rejecting the EPO concept of “closest prior art” resembles the German approach to inventive step which was summarized by the German Supreme Court in the Olanzapin case as follows: “There is no such precedence of the ‘closest prior art’. Only from a retrospective view does it become clear what prior publication comes closest to the invention, and how a developer could have approached the problem, in order to arrive at the solution according to the invention” [52].

Since only one prior art document was at issue in the present case, the Paris CD did not further specify the criteria it would use to limit the number of prior art documents relevant for the assessment of inventive step [53]. Under German practice the justification for choosing a specific prior art document as starting point usually lies in the skilled person’s endeavour to find a better or different solution for a particular purpose than that provided by the state of the art [54]. However, under German patent law it is also possible to have more than one prior art document as starting point, whereby it is irrelevant which of these pieces of prior art the person skilled in the art would consider in the first place. Therefore, a prior art document can be a starting point, even if from an ex post perspective, it is not the “closest” prior art [55]. In a similar way, the EPO allows several starting points [56].

In the course of the proceedings before the Paris CD not the Claimant but the Defendant had raised two other pieces of prior art as possible starting points for the evaluation of inventive step. The court did not consider these documents because it was of the opinion that the Claimant defines the scope for evaluation of a revocation action. According to the Paris CD, the UPC does not evaluate reasons for revocation that the Claimant has not raised [57]. Under German law similar principles apply. The German Supreme Court has held that a claimant who argues in nullity proceedings that the subject matter of the patent at issue was obvious to the person skilled in the art must show that the state of the art included a technical teaching from which the person skilled in the art could use its expertise to develop the subject matter of the invention. The claimant must also show the technical and other factual aspects from which the patent court is to draw the legal conclusion that the person skilled in the art also had occasion to pursue the path objectively made possible for the skilled person on the basis of its expertise and skills [58]. It is not upon the court to supplement the claimant’s incomplete pleading, which means that also in German proceedings the court will not evaluate reasons for revocation that the claimant has not raised [59]. Only in special circumstances German courts have made an exception to this general rule. The German Supreme Court, for instance, regarded it as permissible that in first instance nullity proceedings the Federal Patent Court had considered at its own motion a prior art document which was not initially asserted by the claimant against the patent in suit but was only mentioned in another piece of prior art introduced by the claimant into the nullity proceedings. At least in the nullity appeal proceedings the claimant relied on this prior art document, though [60]. In another nullity action the Federal Patent Court once held that if a prior art document is known to the court and is clearly relevant to the assessment of patentability, it must be taken into account in the decision-making process even if it has not been submitted by the parties [61]. However, it should be noted that in this case, none of the parties objected to the introduction of this state of the art into the proceedings [62]. Despite these exceptional cases decided by the German Supreme Court and the Federal Patent Court it is more likely that in the present case German courts would have decided in line with the Paris CD and would have declined to consider the prior art documents at issue in the context of inventive step.

3. Inducement/suggestion for further development towards the claimed invention

The Paris CD found that the claimed invention differed in one feature – the position of the heater chamber – from the single prior art document which served as starting point for the court’s inventive step assessment. According to the Paris CD, there was no suggestion in the state of the art, relied upon by the Claimant, to arrive at this feature. Therefore, the court concluded that what was claimed as an invention did not follow from the prior art in such a way that the skilled person would have found it in his attempt to solve the underlying problem. The Paris CD also held that the feature at issue did not belong to the common general knowledge at the priority date of the patent in suit [63].

The findings of the Paris CD resemble the German practice which as rule – in line with the EPO’s “could would” approach – requires for obviousness that a solution for the technical problem is not only discernible but that there are additional inducements or suggestions to search for the solution of the technical problem in the direction of the claimed invention [64].

In exceptional cases no inducement or suggestion is required. The fact that a piece of technical information belongs to the common general knowledge is not sufficient, though, to render a technical solution using this information obvious [65]. However, the use of a particular means may be obvious even without a particular inducement or suggestion if this particular means can be considered by the skilled person for a large number of applications, belongs to the general technical knowledge of the skilled person concerned, the use of the functionality in question is objectively appropriate in the context under consideration, and no special circumstances can be identified that would make the application of this particular means impossible, difficult or otherwise impractical from a technical point of view [66].

IV. United Kingdom

There appears to have been few comparisons made in the literature and other reports between the approach of the UK Courts to inventive step and that of the UPC. However, it is useful to compare these jurisdictions in the context of the Paris CD’s decision between NJOY Netherlands and JUUL Labs International because of the UK now being outside of the jurisdiction of the UPC as a non-EU member state [67]. Any similarities and differences are particularly useful for parties to be aware of, especially parties seeking to enforce or challenge European patents validated in the UK alongside UPC Member States.

According to the UK Intellectual Property Office (UKIPO)’s Manual of Patent Practice [68], a text which is not binding on the UK Courts but which provides useful guidance for the Patent Office when examining applications in a similar vein to the EPO’s Guidelines for Examination, the test for inventive step or obviousness should, as far as is possible, be an objective one. Specifically, it is warned against focusing too heavily on the term “step” in “inventive step” and looking at the steps which were actually taken by the inventor, and instead the choice of the word “activity” in the French and German texts of Article 56 EPC is highlighted. With a focus on “activity”, it is alleged to be necessary to ask by what routes it would have been possible for the skilled person to proceed to the goal (i. e., the invention) from the starting point, considering how obstacles might be overcome or avoided on any such route, not only that followed by the inventor.

This focus on the term “activity” in the French and German texts of Article 56 EPC is also found in the Paris CD’s decision under discussion herein. However, the Paris CD relied on this term not in the context of routes or obstacles from the starting point, but rather to hold that “an activity can be motivated by an underlying problem”. In other words, the problem that the claimed subject-matter sets out to solve – irrespective of the starting point – provides the framework within which the skilled person is taking the “next steps”. The Paris CD explained that what is decisive is whether what is claimed as an invention did or did not follow from the prior art in such a way that the skilled person would have found it in his attempt to solve the underlying problem on the basis of its knowledge and skills, for example by obvious modifications of what was already known [69].

The UKIPO also prefers a structured approach to the assessment of inventive step and indeed the Manual of Patent Practice includes a dedicated section to “The four-step Windsurfing approach” as was formulated by the Court of Appeal in Windsurfing International Inc. v Tabur Marine (Great Britain) Ltd [70]. This approach was restated and elaborated by Lord Justice Jacob sitting in the Court of Appeal in Pozzoli SPA v BDMA SA [71] and has become known as the Windsurfing/ Pozzoli test. The steps of this test are as follows: I(a). Identify the notional “person skilled in the art” I(b). Identify the relevant common general knowledge of that person II. Identify the inventive concept of the claim in question or if that cannot readily be done, construe it; III. Identify what, if any, differences exist between the matter cited as forming part of the “state of the art” and the inventive concept of the claim or the claim as construed; IV. Viewed without any knowledge of the alleged invention as claimed, do those differences constitute steps which would have been obvious to the person skilled in the art or do they require any degree of invention?

There are several similarities between this test and the approach taken by the Paris CD in the present decision. In particular, the dedicated identification of the notional “person skilled in the art”, and the holistic, fourth question of “do those differences constitute steps which would have been obvious…?”. As emphasised by Lord Justice Jacob, who gave judgement on behalf of the Court of Appeal in Actavis UK Ltd v Novartis AG [72], the Windsurfing/Pozzoli test differs significantly from the EPO’s problem-solution approach at least in the lack of formulating an objective technical problem. Instances in which this problem is “reformulated” from that set out in the patent was viewed by the UK Court as the weakest part of the EPO’s approach to assessing inventive step; it was held to introduce limitations into the assessment since it risks the danger of hindsight, especially when the court artificially creates a problem which is supposed to be solved by the invention, or where the invention involves perceiving that there is a problem or in appreciating that a known problem can be solved. In those cases, the Court considered it more appropriate to apply the fourth step of the Windsurfing/Pozzoli test.

The UK Courts’ approach to inventive step is, however, different from that of the Paris CD in that there is a requirement to identify the relevant common general knowledge of the “notional person skilled in the art” before considering the “differences” with the starting point. As explained in the UKIPO’s Manual of Patent Practice, this is important because the first three steps of the Windsurfing/Pozzoli approach are “to put one in the proper frame of mind to answer the question posed in the fourth step” [73]. Rather than relying on the “underlying problem” for the “motivation” of an “activity”, the fourth question of the Windsurfing/ Pozzoli test is also asked with reference to such knowledge of the skilled person and the “inventive concept” of the claim. Such differences are interesting in the context of the decision from the Paris CD.

As already noted above, the claimed invention differed from the starting point (Cohen) in that the heater is affixed to a first end of the cartridge, which means that the location of at least the majority of the parts that make up the heater, including the heater chamber, is at a first end of the cartridge. The Paris CD acknowledged in their decision that from his common general knowledge: “the skilled person knows that one way of obtaining condensation is to cool the fluid” and that with this knowledge, they would realize that the “placement of the heater, including the heater chamber, at a first end of the cartridge and the placement of the mouthpiece at a second end of the cartridge provides the opportunity to maximise the joint length of the first condensation chamber and the second condensation chamber, thereby increasing the travel time of the fluid and thereby increasing the cooling time of the fluid, allowing for more time to achieve condensation” [74].

It was also acknowledged by the Paris CD that “To reflect on the parameters of the inhalable aerosol that is inhaled by the user is an intrinsic motivation in the field of devices for generating an inhalable aerosol” [75]. However, the Paris CD ultimately found the claims to be inventive because there was no explicit teaching in the state of the art relied upon by NJOY Netherlands to affix a heater, which comprises a heater chamber, to a first end of the cartridge and to affix a mouthpiece to a second end of the cartridge. Hence, the Paris CD found that the invention “did not follow from the prior art in such a way that the skilled person would have found it in his attempt to solve the underlying problem on the basis of its knowledge and skills, for example by obvious modifications of what was already known” [76]. The application of the Windsurfing/ Pozzoli test appears likely to have led to a different conclusion.

It appears from the Paris CD’s comments on the common general knowledge of the person skilled in the art, that the differences between the claim and the starting point may be deemed “obvious” when considered with a basic question of “do they require any degree of invention?”. The “inventive concept” – namely to increase the travel time of the fluid and thereby increase the cooling time of the fluid, allowing for more time to achieve condensation – is arguably the implementation of the common general knowledge concerning maximising the length of two condensation chambers and placing the heater at a first end and the mouthpiece at a second end.

V. Conclusions

Leaving aside for a moment the UPCA and the corresponding EU legislation on European patents with unitary effect, the conventional side of the European patent system comprises the following actors. On the one hand, there is the EPO which provides for examination proceedings up to the grant of a European patent as well as opposition proceedings following the grant of a European patent [77]. There is also the Technical Boards of Appeal of the EPO who decide on appeals from decisions of the examination and opposition divisions. On the other hand, domestic courts in the Contracting States to the EPC are competent to revoke the respective national parts of granted European patents pursuant to Article 138 EPC [78].

The EPO and the domestic courts strive to achieve a coordinated interpretation of the EPC and the harmonised national patent laws.79 Nevertheless, there are some differences between the practice of the EPO and the case law of the domestic courts in the application of the EPC, in particular with respect to inventive step pursuant to Article 56 EPC [80].

These differences between EPO practice and domestic case law on Article 56 EPC are based, inter alia, on the fact that the EPO is not endowed with the competence to provide authoritative interpretations of the EPC which are legally binding on the Contracting States to the EPC, while at the same time the Contracting States are not obliged to align their national patent laws to EPO practice [81]. Furthermore, at least in the UK there seems to be an understanding going back to the Patents Act 1949 that the standards to be applied to inventive step by the patent office and the courts, respectively, do not necessarily have to be the same, even though such an understanding is not reflected in the wording of Article 56 EPC [82]. The pros and cons of the different approaches to Article 56 EPC are the subject of an ongoing debate [83].

With the entering into force of the UPCA the situation has become even more complex since as of June 1, 2023 the UPC, a supranational tribunal, has the exclusive competence subject to Article 83 UPCA to adjudicate disputes regarding European patents and European patents with unitary effect in currently 18 Contracting Member States (CMS) all of which are at the same time Contracting States to the EPC [84]. Among other things, the UPC has been vested with the power pursuant to Article 65(2) UPCA to revoke European patents and European patents with unitary effect on the grounds referred to in Article 138(1) EPC, including lack of inventive step in accordance with Article 138(1)(a) and Article 56 EPC [85]. Revocation actions under Article 32(1)(d) and (e) UPCA can be brought before the UPC in parallel to EPO opposition/ appeal proceedings [86].

Thus, with the UPC another actor has been added to the European patent system which is competent to decide on the validity of European patents and European patents with unitary effect. Even though Article 24(1)(c) UPCA stipulates that the UPC shall base its decisions on the EPC, this obligation does not comprise the EPO practice, including the case law of the Boards of Appeal of the EPO on inventive step. This interpretation of Article 24(1)(c) UPCA is confirmed e contrario by the fact that the definition of the term “EPC” in Article 2(d) UPCA only refers to the EPC as such whereas the definition of “Union law” in Recital 13 of the preamble of the UPCA explicitly mentions the case law of the Court of Justice of the EU (CJEU). If you look at the question from the perspective of the EPO, the result is no different because the EPO is not authorised to provide binding interpretations of the EPC [87]. Therefore, the UPC, like the domestic courts, is not bound by EPO practice. However, this does not imply that the UPC is exempted from paying due attention to the EPO practice which is one of the cornerstones of the European patent system [88]. Rather, the UPC should strive for an interpretation of the EPC which is coordinated with both, the case law of the domestic courts and EPO practice. Such a policy would enhance legal certainty and prevent conflicting decisions by, for instance, the EPO and the UPC [89]. Taking into account not only the case law of the courts of one or two CMS but of as many domestic courts as possible as well as the EPO would also help to counter the risk that individual CMS or other stakeholders feel marginalised. This would further strengthen the overall acceptance of the UPC [90].

Notes

1. See Deichfuß VPP-Rundbrief Nr. 1/2018, 9.
2. See with respect to Germany and the UK: Haedicke/Timmann PatR-HdB/Nägerl, 2. edn., 2020, § 4 mn. 305 et seq.; Actavis UK Ltd v Novartis AG [2010] EWCA Civ 82 (February 17, 2010).
3. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 – NJOY Netherlands/Juul Labs International.
4. See UPC (CoA), May 23, 2025 – UPC CoA 7/2025, GRUR-RS 2025, 10975 – NJOY Netherlands/Juul Labs International.
5. See EPO, Guidelines for Examination, Part G, Chapter VII.5 (April 2025 edition).
6. See UPC (LD Munich), April 4, 2025 – UPC CFI 501/2023, GRUR-RS 2025, 6253 mn. 233 et seq. – Edwards Lifesciences/Meril.
7. See EPO (Enlarged Board of Appeal), June 18, 2025 – G 1/24, GRUR-RS 2025, 13433 (headnote) – Heated aerosol.
8. See EPO (Enlarged Board of Appeal), June 18, 2025 – G 1/24, GRUR-RS 2025, 13433 mn. 15 – Heated aerosol.
9. See UPC (CoA) GRUR 2024, 527 – NanoString Technologies/10x Genomics, as rectified by UPC (CoA), March 11, 2024 – UPC CoA 335/2023, GRUR-RS 2024, 4034 – NanoString Technologies/10x Genomics.
10. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.2 et seq. – NJOY Netherlands/Juul Labs International.
11. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.5 – NJOY Netherlands/Juul Labs International.
12. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.23 – NJOY Netherlands/Juul Labs International.
13. See EPO (Technical Board of Appeal), January 25, 2021 – T 1370/15, GRUR-RS 2021, 896 – Broadcast processing apparatus and control method thereof.
14. See EPO, Guidelines for Examination, Part G, Chapter VII.5.2 (April 2025 edition).
15. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.43 – NJOY Netherlands/Juul Labs International.
16. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.43 – NJOY Netherlands/Juul Labs International.
17. See EPO (Technical Board of Appeal), April 23, 2015 – T 2255/10, BeckRS 2015, 134088 – Method for producing silicon wafer.
18. See EPO (Enlarged Board of Appeal), March 23, 2023 – G 2/21, OJ EPO 2023, A85, GRUR-RS 2023, 9088 – Reliance on a purported technical effect for inventive step (plausibility).
19. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.43 – NJOY Netherlands/Juul Labs International.
20. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.6 – NJOY Netherlands/Juul Labs International.
21. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.15 – NJOY Netherlands/Juul Labs International.
22. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 Rn. 10.16 – NJOY Netherlands v Juul Labs International.
23. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.44 – NJOY Netherlands/Juul Labs International.
24. See Keukenschrijver, FS Bornkamm, 2014, 677; Deichfuß VPP-Rundbrief 1/2018, 9; Brändle GRUR 2021, 147; Gröning GRUR 2021, 206; König GRUR 2021, 277; Köllner Mitt. 2023, 202; Ackermann Mitt. 2023, 377; Ackermann Mitt. 2024, 111; Engels/Ackermann GRUR 2024, 641; Engels/Ackermann GRUR 2024, 729; Engels/Wismeth, FS Kühnen, 2024; Deichfuß GRUR Patent 2024, 94; Meier-Beck GRUR Patent 2024, 178; Gröning GRUR Patent 2024, 442; Meitinger Mitt. 2025, 12.
25. See Engels/Ackermann GRUR 2024, 641; Engels/Ackermann GRUR 2024, 729.
26. See Deichfuß GRUR Patent 2024, 94.
27. See Meier-Beck GRUR Patent 2024, 178.
28. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.3 – NJOY Netherlands/Juul Labs International.
29. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.4 – NJOY Netherlands/Juul Labs International.
30. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.5 – NJOY Netherlands/Juul Labs International.
31. See Benkard PatG/Asendorf/Schmidt/Tochtermann, 12. Aufl., 2023, PatG § 4 mn. 22 et seq.
32. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.1 to 7.45 – NJOY Netherlands/Juul Labs International.
33. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.43 and 7.45 – NJOY Netherlands/Juul Labs International.
34. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.44 – NJOY Netherlands/Juul Labs International.
35. See BGH GRUR 1991, 811 (813 f.) – Falzmaschine; Engels/Ackermann GRUR 2024, 641 (645 et seq.); Deichfuß GRUR Patent 2024, 94 mn. 25; Meier-Beck GRUR Patent 2024, 178 mn. 54 et seq.; Gröning GRUR Patent 2024, 442 mn. 13 et seq.
36. See BGH GRUR 2010, 602 mn. 27 – Gelenkanordnung.
37. See BGH GRUR 2001, 232 – Brieflocher; BGH GRUR 2004, 47 – blasenfreie Gummibahn I; UPC (CoA) GRUR 2024, 527 (headnote 2) – NanoString Technologies/ 10x Genomics, as rectified by UPC (CoA), March 11, 2024 – UPC CoA 335/2023, GRUR-RS 2024, 4034 – NanoString Technologies/10x Genomics.
38. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.42 – NJOY Netherlands/Juul Labs International.
39. See BGH GRUR 2010, 602 mn. 27 – Gelenkanordnung.
40. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.43 and 7.45 – NJOY Netherlands/Juul Labs International.
41. See EPO, Guidelines for Examination, Part G, Chapter VII.5.2 (April 2025 edition).
42. See BGH GRUR 2010, 44 mn. 14 – Dreinahtschlauchfolienbeutel; BGH GRUR 2015, 356 mn. 9 – Repaglinid; BGH GRUR 2022, 67 mn. 10 – Stereolithographiemaschine; BGH GRUR 2025, 239 mn. 21 – LP-Filterparameter- Umwandlung.
43. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.6 and also 10.16 – NJOY Netherlands/Juul Labs International.
44. EPO (Opposition Division), Annex to the communication – opposition, February 7, 2023, EP3504991, mn. 2.4.3.2.
45. See BGH GRUR 1991, 811 (814) – Falzmaschine; BGH GRUR 2010, 44 mn. 14 – Dreinahtschlauchfolienbeutel; BGH GRUR 2015, 356 mn. 9 – Repaglinid; BGH GRUR 2015, 352 mn. 15 et seq. – Quetiapin; see EPO, Guidelines for Examination, Part G, Chapter VII.5.2 (April 2025 edition).
46. See BGH GRUR 2024, 1432 mn. 14 – Mirabegron.
47. BGH GRUR 2015, 356 mn. 9 – Repaglinid.
48. BGH GRUR 2022, 67 mn. 10 – Stereolithographiemaschine; BGH GRUR 2024, 1432 mn. 13 – Mirabegron; BGH GRUR 2025, 239 mn. 22 – LP-Filterparameter- Umwandlung.
49. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.44 – NJOY Netherlands/Juul Labs International.
50. See BGH GRUR 2011, 607 mn. 19 – kosmetisches Sonnenschutzmittel III; BGH GRUR 2015, 352 mn. 13 – Quetiapin; BGH GRUR 2024, 1432 mn. 20 – Mirabegron; Deichfuß GRUR Patent 2024, 94 mn. 16.
51. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.5 – NJOY Netherlands/Juul Labs International.
52. See BGH GRUR 2009, 382 mn. 51 – Olanzapin.
53. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.5 – NJOY Netherlands/Juul Labs International.
54. See BGH GRUR 2009, 382 mn. 51 – Olanzapin; BGH GRUR 2009, 1039 mn. 20 – Fischbissanzeiger; BGH GRUR 2017, 148 mn. 42 et seq. – Opto- Bauelement; BGH GRUR 2017, 498 mn. 28 – Gestricktes Schuhoberteil; BGH GRUR 2021, 1049 mn. 31 – Zahnimplantat.
55. See BGH GRUR 2016, 1023 mn. 36 – Anrufroutingverfahren; BGH GRUR 2017, 148 mn. 44 et seq. – Opto-Bauelement.
56. See EPO, Guidelines for Examination, Part G, Chapter VII. 5.1 (April 2025 edition).
57. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.21 et seq. – NJOY Netherlands/Juul Labs International.
58. See BGH GRUR 2013, 1272 mn. 36 – Tretkurbeleinheit; BGH GRUR 2015, 365 mn. 49 – Zwangsmischer.
59. See Benkard PatG/Schäfers/Schnurr, PatG § 87 mn. 12 et seq.
60. See BGH, July 1, 2003 – X ZR 8/00, BeckRS 2003, 8495 – Gleitvorrichtung.
61. See BPatG, May 4, 2015 – 5 Ni 60/12 (EP), BeckRS 2015, 17323 mn. 32 – Fahrradgangschaltung.
62. See BPatG, May 4, 2015 – 5 Ni 60/12 (EP), BeckRS 2015, 17323 mn. 29 – Fahrradgangschaltung.
63. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.15 et seq. – NJOY Netherlands/Juul Labs International.
64. See BGH GRUR 2009, 746 mn. 20 – Betrieb einer Sicherheitseinrichtung; BGH GRUR 2013, 363 mn. 27 – Polymerzusammensetzung; Deichfuß VPPRundbrief 1/2018, 9 (12 et seq.); Deichfuß GRUR Patent 2024, 94 mn. 34 et seq.
65. See BGH GRUR 2018, 716 mn. 28 – Kinderbett.
66. See BGH GRUR 2014, 647 mn. 26 – Farbversorgungssystem; BGH GRUR 2018, 509 mn. 113 – Spinfrequenz; BGH GRUR 2018, 716 – Kinderbett; BGH GRUR 2020, 1074 mn. 49 – Signalübertragungssystem; BGH GRUR 2024, 1790 mn. 43 – Scheibenbremse III; Deichfuß VPP-Rundbrief 1/2018, 9 (14 et seq.).
67. See UPC website https://www.unified-patent-cou... ons?mr=GB.
68. See UKIPO, Manual of Patent Practice (Published: February 19, 2016, Updated: April 1, 2025), Section 3.04 at www.gov.uk/guidance/manual-of-... atent-practice-mopp/section-3-inventive-step.
69. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.6 – NJOY Netherlands/Juul Labs International.
70. See Windsurfing International v Tabur Marine (Great Britain) Ltd [1985] R. P. C. 59.
71. See Pozzoli SPA v BDMO SA [2007] EWCA Civ 588 (June 22, 2007).
72. See Actavis UK Ltd v Novartis AG [2010] EWCA Civ 82 (February 17, 2010).
73. See UKIPO, Manual of Patent Practice (Published: February 19, 2016, Updated: April 1, 2025), Section 3.15 at www.gov.uk/guidance/manual-of-... atent-practice-mopp/section-3-inventive-step.
74. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.37 – NJOY Netherlands/Juul Labs International.
75. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 7.44 – NJOY Netherlands/Juul Labs International.
76. See UPC (CD Paris), November 5, 2024 – UPC CFI 315/2024, GRUR-RS 2024, 30221 mn. 10.6 – NJOY Netherlands/Juul Labs International.
77. See Haedicke/Timmann PatR-HdB/Landry, § 6 mn. 1 et seq.; Haedicke/ Timmann PatR-HdB/Landry/Harbsmeier, § 7 mn. 1 et seq.
78. See Benkard EPÜ/Scharen, 4. Aufl., 2023, EPÜ Art. 138 mn. 1 et seq.
79. See EPO (Enlarged Board of Appeal), December 5, 1984 – G 1/83, BeckRS 1984, 30478513 mn. 6 – Second medical indication; EPO (Enlarged Board of Appeal) GRUR Int. 2010, 608 (610 et seq.) – Programs for computers; EPO (Enlarged Board of Appeal), June 18, 2025 – G 1/24, GRUR-RS 2025, 13433 mn. 33 et seq. – Heated aerosol; BGH GRUR Int. 1987, 357 (359) – Tollwutvirus.
80. See with respect to Germany and the UK: Haedicke/Timmann PatR-HdB/ Nägerl, § 4 mn. 305 et seq.; Actavis UK Ltd v Novartis AG [2010] EWCA Civ 82 (February 17, 2010).
81. See Bruchhausen GRUR Int. 1983, 205 (207 et seq.).
82. General Electric Company’s Applications (Patent, subject matter) [1964] R. P. C. 413 (452 et seq.); Actavis UK Ltd v Novartis AG [2010] EWCA Civ 82 (February 17, 2010); MGK/Pagenberg, 5. Lieferung, Art. 56 EPÜ mn. 70.
83. See Busse/Keukenschrijver/Keukenschrijver, PatG, 9. Aufl., 2020, § 4 mn. 21; Engels/Ackermann GRUR 2024, 641; Engels/Ackermann GRUR 2024, 729.
84. See Bopp/Kircher EurPatentprozess-HdB/Kircher, 3rd edn., 2025, § 1 mn. 8.
85. See Bopp/Kircher EurPatentprozess-HdB/Burrichter/Kirchhofer § 14 mn. 149.
86. See Bopp/Kircher EurPatentprozess-HdB/Burrichter/Kirchhofer, § 14 mn. 105.
87. See Bruchhausen GRUR Int. 1983, 205 (207 et seq.).
88. See UPC (CoA), June 19, 2025 – UPC CoA 405/2024, GRUR-RS 2025, 13714 mn. 21 – Alexion/Amgen; UPC (LD Munich), April 4, 2025 – UPC CFI 501/ 2023, GRUR-RS 2025, 6253 mn. 233 et seq. – Edwards Lifesciences/Meril.
89. See UPC (CD Munich), July 16, 2024 – UPC CFI 1/2023, GRUR 2024, 1625 – Sanofi-Aventis/Amgen; EPO (Opposition Division), Grounds for the decision (Annex) – Opposition, May 21, 2025, EP3666797
90. See Klopschinski GRUR Patent 2024, 568 (572)