Joris DeeneAnyone who brings a product to market that is similar to a patented one does not automatically avoid patent infringement. But neither is strong similarity sufficient to establish infringement - even through the so-called doctrine of eqquivalents. This is evident from a judgment of the French-speaking business court in Brussels on Sept. 22, 2025, in the case of Out and Out Chemistry v. Trasis. The patentee was vindicated on the validity of its European patent, but suffered defeat on the infringement claim because an essential feature of the invention was not reproduced.
The facts
Out and Out Chemistry (R&D) holds European patent EP 3 297 977, with priority date May 20, 2015. The patent protects a process and associated apparatus for the serial production of radiopharmaceuticals - more specifically, fluorine-18-based radiotracers used in nuclear medicine for imaging and treatment. The core of the invention involves “reconditioning” a so-called QMA cartridge (an ion exchanger) between successive synthesis cycles so that it can be used multiple times instead of being discarded after each cycle. In doing so, the patent explicitly describes that the successive syntheses take place on a different cartridge each time.
Trasis markets synthetizers and cassettes under the names “All-in-one,” “FDG Dual,” “FDG Dual+” and “FDG Quad.” According to R&D, these products apply its invention: Trasis also reuses its QMA cartridge between synthesizers. O&O therefore sought a cease-and-desist order for both the Belgian and French parts of its patent. Trasis counterclaimed for invalidity of the Belgian part and challenged the jurisdiction of the Brussels court for the French part. Prior to that, R&D had performed a seizure concerning counterfeiting (art. 1369bis/1 Jud.C.) at Trasis.
The decision
Apprehend ruling on the French part
The court stays judgment for claims related to the French hatch. Reason: Trasis brought an action for annulment of the French hatch in Paris. For this, the court refers to the May 12, 2011 Court of Justice ruling (C-144/10), which held that “the validity of the patent concerned is an essential premiss, in particular in any infringement action.” Good administration of justice, according to the court, precludes deciding the French infringement claim until the Paris court has ruled on the validity of the French part.
Validity of the Belgian section
The counterclaim for invalidity is dismissed on all grounds. The court successively runs through the three grounds for invalidity asserted under Art. 138 European Patent Convention (EPC) and Art. XI.57 Code of Economic Law (CEL).
The description of the patent is sufficiently clear: it discloses both the technique (reconditioning with carbonate solution or pure water) and the concentration range within which the reconditioning operates. The position of the person skilled in the art - defined by the court as a team consisting of a radiochemist as well as a radiopharmacist - confirms that the invention is reproducible.
On the issue of inventive step, the court applies the problem-solving approach of the European Patent Office. Trasis argues several combinations of prior publications, including microfluidics (Leonardis and Lebedev). The court rejects these combinations: microfluidics operate on a scale a thousand times smaller than classical radiopharmaceuticals, and are described as still experimental in a 2021 IAEA report. A professional would not simply combine two documents from different technical fields. Even the combination of classical papers (Berndt, Lazari) does not provide evidence, because none of them reveals the reconditioning and reuse of the QMA cartouche for multiple production cycles.
Finally, the novelty criticism is rejected. Trasis argued that its own prior products - sold before the priority date - would be novelty harm. The court pointed out that for an anteriority to be novelty-harming, all features (and not just the essential ones) must clearly, precisely and directly result from the prior art. Trasis itself acknowledges that its products do not reproduce the “multi-cassette” aspect of the invention, and thus can hardly rely on its own products.
No literal nor equivalent infringement
This is where the verdict tilts. Although the patent is declared valid, the court rules that Trasis' products do not infringe.
The court dissects claim 1 into five features. The crucial features 1.3 and 1.4 require that the steps of the process be repeated “using a different cassette” for radiopharmaceutical synthesis. In contrast, the expert report notes that the Trasis cassettes are “configured to repeat the steps of capture, eluting and preparation on the same cassette.” The “All-in-one” synthesizer is not designed to allow multiple cassettes to be attached simultaneously.
O&O objected that the plurality of cassettes is not an essential feature of the invention, and that the reuse of one cassette provided interim rinse would be equivalent to it. The court did not follow this. It applied the classic “function-way-result” test and found that the three elements were not satisfied: the Trasis process allows only the production of one type of radiotracer (FDG), while the patent covers the production of several types in series; moreover, the Trasis process requires complete cleaning (CIP) of all cassette components between each cycle, resulting in more waste and risk of loss of efficiency.
No unfair market practices
The claim that Trasis made misleading claims about its products is also rejected. Although the cited wordings in commercial documents were “clumsy,” according to the court, that is not sufficient for a violation of Sections VI.104 and VI.105 of the CEL.
Legal analysis and interpretation
The doctrine of equivalents extends beyond literal similarity - but not endlessly
The doctrine of equivalents, enshrined in Art. XI.28(2) CEL, protects the patentee against parties who adapt the invention so that it formally falls outside the wording of the claims, but functionally does the same thing. However, the threshold is high: the claimed equivalence must hold for each of the three criteria (function, manner, result).
In the Brussels judgment, the equivalence analysis falls apart on the third criterion. Indeed, the Trasis process does not achieve “substantially the same result”: it can provide only one type of radiotracer, where the patent explicitly describes the production of different types in the same series (§ [0012] and [0027] of the patent). That difference in result is not a detail - it is linked to the actual economic added value of the invention. Thus, the doctrine of equivalents cannot be used to still bring a fundamentally more limited process under patent protection.
The “essential characteristic” paradox
The judgment exposes an interesting tension that any patentee must consider. O&O argued simultaneously on two levels: on novelty, it argued that its invention contains at least one “essential” feature that was missing in Trasis’ earlier products (the multi-cassette aspect), while on the infringement claim, it argued that the very same feature was not essential, in order to still bring the Trasis process under its patent. The court here implicitly refers to the doctrine developed by the Court of Appeal of Liège and also confirmed by M. Buydens: “a difference relating to an essential feature of the protected invention is not a secondary or superficial difference” (M. Buydens, Droit des brevets d'invention, Larcier, 2020, no. 943).
The message for patent holders is clear: what trumps the odds in invalidity litigation - the essential features that make the invention original - becomes a double-edged sword in infringement litigation. The more a patentee emphasizes the essential features to defend validity, the tighter it tightens its own protection perimeter.
The missed connection at BSH Hausgeräte/Electrolux
On the procedural front, one observation deserves attention. The Brussels court upholds the French infringement claim based on a more than 14-year-old ruling (ECJ May 12, 2011, C-144/10) and on the basis of the preliminary question raised in 2022 in Case C-339/22, which it presents as pending. The latter question has since been answered: in its ruling of February 25, 2025, the Grand Chamber of the Court of Justice in BSH Hausgeräte/Electrolux (C-339/22) held that a court of the defendant's state of domicile, which, under Art. 4(1) Regulation 1215/2012 is competent to rule on the infringement of a patent granted in another Member State, even if the validity of that patent is challenged by way of exception. The court does not have jurisdiction to rule on validity with erga omnes-effect - that jurisdiction remains exclusively reserved to the courts of the granting state under Article 24(4) - but it may assess validity inter partses for the purpose of the infringement question.
That ruling had been rendered seven months earlier than the Brussels judgment but is not mentioned in it. This does not necessarily mean that the judgment is incorrect on this point - the court stayed the case for reasons of “due process,” which is discretionary. But BSH Hausgeräte did change the legal basis for this stay: since Feb. 25, 2025, the validity of a foreign patent is no longer a sine qua non that prevents the Belgian court from ruling on the infringement. For future cases, the standard response to such a jurisdictional exception is likely to be different.
Specifically, what does this mean?
For patent holders and their agents. The wording of the claims determines the scope of protection. Any feature included in the claims becomes a potential stumbling block to infringement: a competitor who performs that one feature differently may rely on it. At the same time, the doctrine of equivalents provides a safety net, but only when function, manner and result coincide. It is therefore wise when drafting a patent to identify in advance which features are truly “essential” to the added value of the invention, and which features are merely accessory - and not to include the latter unnecessarily.
For competitors and R&D departments. The ruling confirms that “design around” remains technically and legally possible. When an invention can be reproduced with the omission of an essential feature, there is room for a competing product without patent infringement. However, a thorough safeguard analysis (freedom-to-operate) remains appropriate, with particular attention to the doctrine of equivalents.
For litigants in cross-border disputes. Since BSH Hausgeräte, the question of jurisdiction has been different. A patentee who wants to bring all national hatches of a European patent before a single forum has strong arguments for doing so - even if the validity is challenged in each of those member states. Those who, as defendants, seek stay of the judgment can no longer simply rely on Art. 24(4) Regulation 1215/2012; the justification will have to rely on concrete procedural grounds.
Frequently asked questions (FAQ)
What is the doctrine of equivalents in patent law?
The doctrine of eqquivalents is an extension of literal patent protection. It allows the patentee to act against a product or process in which one of the patented features has been replaced by another feature that performs substantially the same function, in substantially the same manner, to achieve substantially the same result (the so-called “function-way-result” test). The doctrine of equivalence is enshrined in Belgium in Article XI.28, second paragraph CEL.
Can a Belgian court rule on patent infringement in other EU member states?
Yes. Since the ruling of the Court of Justice in BSH Hausgeräte v. Electrolux of Feb. 25, 2025 (C-339/22), it has been established that a Belgian court with jurisdiction over a defendant domiciled in Belgium under Art. 4(1) Brussels Ia Regulation may also rule on the infringement of foreign hatches of a European patent. He may assess the validity inter partses but it cannot declare it null and void erga omnes - that power belongs exclusively to the courts of the granting state.
When is a feature of an invention “essential”?
There is no fixed definition in the law. Courts test on a case-by-case basis, based in part on the description of the patent and the contribution of the feature to the technical function of the invention. A clue can be found in the way the patent presents the feature (central or accessory), in the figures, and in the objective technical problem the invention seeks to solve. A difference involving an essential feature is not a secondary or superficial difference and therefore excludes literal infringement.
Conclusion
This judgment is an instructive illustration of the paradox in which the patentee can find himself. The Brussels judgment, on the one hand, confirms the validity of the patent but, on the other hand, denies any infringement because an essential feature of the invention - production via multiple cassettes - is not reproduced by the competitor. The doctrine of equivalents provides no safety net when the function, manner or result is substantially different. At the same time, the ruling illustrates the procedural challenge of cross-border patent litigation, for which the Court of Justice's BSH Hausgeräte ruling has meanwhile outlined a new framework that will take center stage in future cases.
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