An Analysis of Emerging Jurisprudence from the Milan and Brussels Divisions
The Unified Patent Court (UPC) is the most significant development in European patent litigation for a generation. Central to its design is an efficient and predictable procedural framework. A cornerstone of this framework is the ‘front-loaded’ principle, which requires parties to present all facts, arguments and evidence relating to their case at the earliest possible stage of the proceedings. Enshrined in the UPC’s Rules of Procedure (RoP), this principle marks a departure from the iterative and often protracted litigation styles common in many national jurisdictions.
As the UPC concludes its second year of operation, a body of case law is emerging that provides valuable insight into how its judges will interpret and apply these fundamental principles. Two recent orders, one from the Central Division in Milan in EOFLOW Co., Ltd. v. Insulet Corporation (UPC_CFI_597/2024) and another from the Local Division in Brussels in the OrthoApnea case (UPC_CFI_376/2023), offer a compelling comparison of the practical application of the front-loaded system. While they may initially appear to signal divergent approaches — one strict and the other flexible — a deeper analysis reveals an emerging, nuanced and coherent doctrine that seeks to balance procedural efficiency with the fundamental rights of the parties.
This article will analyse the front-loaded principle as defined in the Rules of Procedure (RoP) and examine how these two key decisions interpret its boundaries, providing essential guidance for litigants navigating this new judicial landscape.
The philosophy of the UPC procedure is clearly articulated in the Preamble to the Rules of Procedure (Paragraph 7), which states that parties ‘shall cooperate with the Court and set out their full case as early as possible in the proceedings’. This is not merely an aspirational statement, but a directive woven into the fabric of the procedural rules.
The primary instruments for enforcing this principle are the rules that govern the initial written pleadings. Rule 13 of the Rules of Procedure (RoP) dictates the exhaustive content required in a Statement of Claim. A claimant must provide the alleged infringing patent claims, as well as a detailed ‘indication of the facts relied on’, ‘evidence relied on’, and ‘reasons why the facts relied on constitute an infringement of the patent claims’, including arguments of law and, where appropriate, an explanation of the proposed claim interpretation. A similar comprehensive obligation is placed on the defendant in their Statement of Defence under Rule 24 of the Rules of Procedure (RoP).
This structure is designed to ensure that, from the outset, the scope of the dispute is clearly defined. This enables the defendant to understand the allegations made against them and prepare an adequate defence, while allowing the court to manage the case efficiently. The principle is further supported by evidence rules, such as Rules 171 and 172 of the Rules of Procedure (RoP), which state that a party asserting a fact must indicate how it will be proven. Furthermore, if a party fails to indicate the means of evidence regarding a contested fact, the court shall take this failure into account when deciding the issue in question.
However, the critical question for practitioners is where the line is drawn. To what extent can a party supplement or amend their case in response to arguments raised by the opposing party? It is here that the EOFLOW and OrthoApnea decisions provide complementary clarification.
Case Analysis 1: EOFLOW v. Insulet – A Strict Stance on Foundational Evidence
In the proceedings before the Milan Central Division, the court considered a revocation action brought by Eflow against a patent held by Insulet. The procedural timeline included the filing of a revocation application and defence, as well as replies to these. Well into the written procedure, EOFLOW introduced a new prior art document, US ‘159 (Flaherty), for the first time in its reply to the revocation defence. Insulet objected, and the court was tasked with deciding on its admissibility.
The court’s decision was unequivocal: the document was inadmissible. The Court’s reasoning provides a powerful affirmation of the strict interpretation of the front-loaded principle, particularly in the context of revocation actions.
The Court stated that, ‘whenever a party proposes to bring an action before the UPC, it must take care to collect in advance the documents supporting the claim’. The procedure before the UPC is, in fact, a front-loaded procedure in which the written procedure enables the parties to exchange replies and rejoinders based on a wealth of stable and consolidated knowledge and documents from the moment the claim is filed. In general, the parties are obliged to present their complete case as early as possible (RoP Preamble, para. 7, last sentence).’
The Court reasoned that, in a revocation action, the claimant is obliged to collect all documents supporting their claim in advance. Introducing prior art at a late stage was deemed contrary to this principle as it prevents the opponent from filing full observations on a crucial point of the legal assessment.
Crucially, the court held that this violated the adversarial principle enshrined in Article 76 of the Unified Patent Court Agreement (UPCA), which stipulates that decisions must be based solely on facts and evidence to which the parties have had the opportunity to respond. EOFLOW was required to prove that the document could not have been submitted earlier; however, it failed to do so. The court noted that, since the initial preliminary injunction action was filed in July 2024, EOFLOW had ample time to conduct a thorough prior art search.
The court also dismissed EOFLOW’s reliance on Rule 263 RoP (‘Leave to change claim or amend its case’), clarifying that this rule ‘clearly refers to changes/amendments to legal claims and cannot be used to introduce new evidence on the same legal claim (revocation)’. The court interpreted the late filing of new prior art as an attempt to modify the subject matter of the dispute rather than as a mere supplementation of evidence. This would require a formal and justified application under Rule 263.
The Milan decision sends a clear message: foundational evidence, such as prior art forming the basis of a nullity claim, must be included in the initial ‘front load’. Parties cannot hold such evidence in reserve to be deployed later in the proceedings.
Case Analysis 2: OrthoApnea case– A Flexible Approach to Responsive Arguments
The case before the Brussels Local Division presented a different scenario. In a General Procedural Application entitled ‘Objections against Equivalence’, the claimant sought to supplement the factual framework and infringement argument with an equivalence argument, and to amend the petitum, in light of the application (or non-application) of the following rules: R. 13.1(l) to (o) RoP: ‘Content of Statement of Claim’; R. 24(b) to (g) RoP: ‘Contents of Statement of Defence’; R. 29(b) and (c) RoP: ‘Lodging of Defence to the Counterclaim for Revocation, Reply to the Statement of Defence and Rejoinder to the Reply’; and R. 263 RoP: ‘Leave to Change Claim or Amend Case’.
The defendants objected, arguing that this constituted an impermissible amendment under the front-loaded system.
However, the Judge-Rapporteur rejected the defendants’ objection, offering a more flexible interpretation of the rules that emphasises fairness and the natural evolution of a legal dispute.
The court’s reasoning was grounded in the purpose of the rules. The Court found that the purpose of Rule 13 RoP is to ‘avoid… overly summary and/or unsubstantiated argumentation, in which a claimant would be limited to raising general pleas without sufficiently elaborating or substantiating them factually, thereby placing the defendant in a position where they cannot effectively defend themselves. When testing this objective against the Statement of Claim, the claimant should be considered a reasonable and prudent person placed in the same circumstances”.
Most importantly, the Brussels court explicitly acknowledged the ‘procedural-evolutive course of a judicial dispute’. It recognised that a claim is followed by a defence and that the claimant must be given the opportunity to respond to it. This right to respond may naturally involve elaborating on existing claims or developing alternative pleas. The court viewed this flexibility as an inherent feature of the system, stating that ‘the right of defence allows the counterparty to adapt or supplement their arguments as they see fit in light of the defence’.
In this context, new arguments based on equivalence were not considered an impermissible modification of the dispute’s subject matter. Instead, they were considered a direct response to the Statement of Defence that fit into the procedural-evolutive course of a judicial dispute. Therefore, a formal application under Rule 263 RoP was not necessary. The court emphasised that the procedural framework itself contains mechanisms to ensure fairness, such as the judge’s ability to extend time limits or organise additional rounds of submissions, in order to safeguard the right to defence.
Synthesizing the Decisions: Two Sides of the Same Coin
At first glance, the Milan court’s strict refusal to admit new evidence and the Brussels court’s willingness to allow new arguments may appear contradictory. However, they define the two sides of a single, coherent boundary: the subject matter of the dispute.
The EOFLOW decision establishes that evidence defining the subject matter of the claim — such as the prior art relied upon in a revocation action — must be presented at the outset. Introducing it later would not merely supplement an argument; it would fundamentally alter the basis of the legal action, thereby changing the subject matter of the dispute itself. This is prejudicial because the defendant has not had a fair opportunity to respond to this new case throughout the procedural stages.
The OrthoApnea decision clarifies that arguments and facts introduced in direct response to the other party’s pleadings which remain within the originally defined subject matter are permissible. Raising an argument for infringement by equivalence in response to a defence challenging literal infringement does not change the core subject matter, which remains the question of whether a specific product infringes a specific patent. It is an evolution of the argument within that established scope.
The key distinction lies in the difference between introducing a new basis for the case (which is impermissible without leave under Rule 263) and building on the existing basis in response to the opponent’s actions (which is permissible as part of the procedural dialogue).
The EOFLOW and OrthoApnea rulings offer invaluable initial guidance on the UPC’s front-loaded procedure. They show that, although the court is committed to enforcing procedural discipline to ensure efficiency, this will not be at the expense of fairness or the right to a fair defence. The emerging doctrine is one of principled flexibility.
For parties litigating before the UPC, the practical implications are clear:
- Meticulous preparation is non-negotiable. The front-loaded system places an immense burden on parties to prepare their entire case before filing. For revocation claimants, this means conducting an exhaustive and definitive prior art search from the outset. For infringement claimants, this means fully articulating all grounds for infringement in the initial Statement of Claim, including pleading in the alternative (e.g. literal infringement and infringement by equivalence), if at all possible.
- Understand the scope of your dispute. The concept of the ‘subject matter of the dispute’ is paramount. Any evidence or argument that could be seen as defining or modifying this subject matter must be included initially.
- Frame responsive submissions carefully: When introducing new arguments or facts in a reply, it is important to present them as a direct and necessary response to the points raised in the statement of defence. This positions the new material as a legitimate part of the procedural dialogue, rather than an ambush.
- Do not rely on Rule 263 as a safety net. As the Milan court made clear, Rule 263 RoP is not a tool for correcting a failure to provide foundational evidence at the outset. It is intended for genuine and justifiable changes to a party’s legal claim, and leave will not be granted lightly.
As the Unified Patent Court continues to hear cases, its jurisprudence will undoubtedly provide more details on these principles. However, the initial indications from Milan and Brussels suggest that the court is successfully setting a precedent that honours the efficiency goals of its front-loaded system, while also ensuring that the procedural fairness essential for robust and just adjudication is preserved.
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Appendix: A Snapshot of Growth at the UPC’s Milan Divisions
A closer look at the UPC’s own statistics reveals the growing importance and level of activity of its Milan-based divisions. Comparing the court’s case load reports from the end of November 2024 with the update from 31 May 2025 reveals a clear trend of increased activity over just six months, particularly within the Milan Local Division (“Milan LD”).
The Milan LD has experienced significant growth in its core activities.
- The number of infringement actions filed in the Milan LD more than doubled, increasing from 7 as of November 2024 to 15 by the end of May 2025.
- Similarly, counterclaims for revocation saw a more than threefold rise, jumping from 2 to 7 in the same period.
- Applications for provisional measures also saw a modest increase from 4 to 5.
- Application for preserving evidence jumped from 1 to 3.
The Milan Central Division (Milan CD), whose primary competence is handling stand-alone revocation actions, has also seen its caseload develop.
- The number of stand-alone revocation actions filed with the Milan CD increased from 7 in November 2024 to 8 by the end of May 2025.
- While the number of infringement actions remained stable at one, the division saw the addition of new case types by May 2025, including one counterclaim for infringement, one request for damages, and one declaration of non-infringement.
This data highlights that the Milan divisions are active and attracting an increasing number of cases. The substantial growth in infringement actions at the Local Division, in particular, signals its emergence as a leading venue for patent enforcement within the new European system.