European Patent System Practice Guide

The core of the European patent system lies in its two-tier structure: while the European Patent Office (EPO) administers a single grant procedure based on the European Patent Convention (EPC), the patent’s effect branches out into national rights in each designated country (bundled patents) after grant.With the launch of the Unified Patent System (UP/UPC) in June 2023, the traditional “country-by-country” approach has been supplemented by the option of “unified effect plus consolidated litigation before the Unified Patent Court,” leading to significant changes in portfolio strategies.In this article, from a patent attorney’s practical perspective, we systematically organize topics ranging from procedural design based on EPC provisions, deadline management, and the latest case law (G 2/21, G 1/22, G 1/24, etc.), to strategies for utilizing the Unified Patent System and cost structures.

Basic Structure and Legal Nature of the European Patent System

The European patent system is operated by the European Patent Organisation under the EPC, with the EPO centrally responsible for grant procedures such as the receipt, search, examination, and grant of applications. In contrast, the effect of a granted patent is subject to the same effect and conditions as a national patent in each designated country (EPC Article 2(2)).

Languages and Official Languages

The official languages of the EPO are English, French, and German. European patent applications must generally be filed in one of these official languages, but filing in other languages is also permitted, provided that a translation is submitted within the prescribed time limit (generally two months from the filing date). Failure to submit a translation may result in deemed withdrawal, so relying on this as a contingency is risky.Upon grant, the specification is published in the procedural language, and the claims must be translated into the remaining two official languages in accordance with Rule 71(3).

Application Procedures and Key Deadlines

The European route consists of two main paths: (A) direct European applications (EP) and (B) Euro-PCT applications entering the European phase from the PCT. In the Euro-PCT route, the EPO, acting as the designated or elected Office, must complete the procedures necessary for entering the European phase (translation, various fees, request for examination, etc.) within 31 months (Rule 159(1)).

Requirements for Application Documents

Article 78 EPC requires the following documents: the request for a European patent, the description, the claims, the drawings (if any), and the abstract.The minimum requirements for the determination of the filing date, as set forth in Article 80 and Rule 40(1), are “an indication that a European patent is sought,” “identification of the applicant and contact information,” and “the description or a reference to a prior application.” If the filing-by-reference method is chosen, attention must also be paid to additional submissions (such as copies).

List of Key Deadlines (Missing these in European practice can be fatal)

Flowchart from Application to Grant

Patentability Criteria and Specification Requirements

Under the EPC, “patentability” is fundamentally based on meeting the requirements of novelty (Art. 54), inventive step (Art. 56), and industrial applicability (Art. 57), with the prerequisite of the invention being eligible and technical in nature (Art. 52).The requirements for the specification focus on workability (Art. 83) and the clarity, conciseness, and support of the claims (Art. 84); in amendment practice, the prohibition on introducing new matter (Art. 123(2)) is the most common "sticking point."

Novelty and Inventive Step

Novelty is structured such that “anything made available to the public before the filing (priority) date” constitutes prior art (Art. 54(2)). In Europe, particularly given that Art. 54(3) (e.g., European applications filed before publication) specifically targets novelty, the hierarchical design of claim sets and the handling of divisional applications are of practical importance.While the statutory definition of inventive step is succinct—"not obvious to a person skilled in the art"—the standard practice follows the EPO’s problem-solution approach, consistently presenting the closest prior art, the differences, the objective technical problem, and the demonstration of the technical effect.

The COMVIK Approach for Software and Simulation Inventions

For software and business-related inventions, the COMVIK approach (where non-technical features are treated as not contributing to inventive step) is a fundamental premise in practice. Enlarged Board of Appeal decision G 1/19 (March 10, 2021) clarified that this framework also applies to simulation inventions, identifying “whether the technical effect goes beyond a standard computer implementation” as the key criterion.

Disclosure Requirements and Claim Interpretation (G 1/24)

Regarding the requirements for disclosure, Article 83 requires “a disclosure that is sufficiently clear and complete to enable a person skilled in the art to carry out the invention,” while Article 84 requires claim clarity and support. The recent landmark decision G 1/24 (June 18, 2025) concluded that even in claim interpretation during patentability examination (Articles 52–57), claims must always be interpreted with reference to the specification and drawings.

Rejection Grounds and EPO Examination Practice

In practical terms, grounds for rejection can be classified as: (a) patentability requirements (Art. 52–57), (b) disclosure requirements (Art. 83/84), (c) amendment restrictions (Art. 123(2)/(3), Rule 137, etc.), (d) Unity (Art. 82), and (e) missed deadlines and unpaid fees (Rules 38, 39, 70, 71(3), etc.). The areas where the greatest differences emerge in EPO proceedings are the design of amendments, the demonstration of technical effects, and the judgment required to eliminate potential procedural pitfalls at key junctures.

Amendment Strategy and Additional Matter (Art. 123(2))

Regarding amendments, Rule 137 generally prohibits amendments before receipt of the search report, and there are restrictions on additional amendments at the examiner’s discretion (Rule 137(3)). In both cases, compliance with the prohibition on additions (Art. 123(2)) is a fundamental prerequisite.In Europe, an initial specification based on the assumption that “amendments will fix it” is risky; particularly if the description of effects, mechanisms of action, parameter definitions, or the depth of the examples is insufficient, the structure makes it easy for subsequent supplementation to be blocked by Article 123(2).

Demonstration of Technical Effect (G 2/21)

Regarding the technical effect—the core of the “difference” required for inventive step—G 2/21 (March 23, 2023) clarified that post-filing evidence cannot be excluded solely on the grounds that “it was not published before the filing date.”However, this does not mean that any post-filing evidence will automatically be accepted; the evaluation criterion of whether “the effect is included in the technical teaching at the time of filing” remains. Therefore, it is still crucial to design the specification so that it incorporates, at the very least, a reasonable basis for the effect (data, reasoning, or connection to common technical knowledge) at the time of filing.

Risks at the Notice of Intent to Grant (R.71(3)) Stage

The stage following the R.71(3) notification is extremely high-risk, not only in terms of examination compliance but also because the window for correcting errors or omissions rapidly narrows.Payment of the grant fee and publication fee, along with submission of the claim translation, is required within four months, and in practice, this is treated as a non-extendable deadline. Regarding the Druckexemplar (grant text), it is reasonable to ensure consistency among the claims, specification, drawings, reference symbols, and list of cross-references through a dual review process involving both internal and attorney reviews.

Appeals, Objections, Invalidations, and Recent Major Case Law

As a central procedure following grant, a third party may file an opposition with the EPO within “nine months of the publication of the grant notice,” and the grounds for opposition are limited to Article 100. Since an opposition has central effect extending to all designated countries, it significantly impacts litigation risk management (particularly when parallel to central invalidation proceedings under the Unified Patent Court/Unified Patent Court) in terms of whether the patent “fails or is upheld” at the central level; the EPO has also indicated a practice of expediting opposition proceedings for cases equivalent to court litigation.

Appeal Proceedings and the Convergent Approach (RPBA)

Under Art. 108, an appeal must be filed within two months of notification of the decision, with grounds for appeal submitted within four months; payment of the appeal fee is a requirement for validity.In appeal proceedings, managing the timing of submissions and the structure of arguments is critically important in practice due to the convergent approach under the Rules of Procedure (RPBA). It is essential to note that initial actions—such as organizing the set of claims in the first instance, finalizing rebuttals, and timing the submission of evidence—tend to directly influence the final outcome.

Domestic Invalidity and Central Limitation (Art. 105a)

With regard to domestic invalidity, European patents are treated as national patents in each country after grant, and the grounds for revocation (invalidity) in each country are applied in a manner consistent with the categories listed in EPC Art. 138 (lack of patentability, lack of industrial applicability, additional subject matter, claim extension, lack of entitlement, etc.).Furthermore, since the patent proprietor may request the EPO to limit or revoke the patent (Art. 105a), except where opposition proceedings are pending, there is scope to design “central limitation” as a safeguard in dispute strategy.

Summary of Key Case Law

Enforcement of Rights and the Unified Patent System (UP/UPC)

Post-grant enforcement will see two parallel systems coexist: (i) Conventional: Infringement litigation in each national division following validation, and (ii) Unified Patent: Consolidated litigation centered on the European Patent (UP) with unitary effect and the Unified Patent Court (UPC).

Traditional Route and Provisional Protection (Art. 67)

Under the traditional approach, since a European patent has the force of a national patent in each designated country (Art. 2(2)), injunctions, damages, and discovery are determined within the framework of each country’s laws.Although provisional protection may be granted after publication under EPC Art. 67, specific details of such protection (scope of compensation claims, translation requirements, etc.) vary by country. Consequently, from a litigation strategy perspective, it is necessary to design a country-by-country approach regarding “when, in which country, and what relief to seek.”

Key Points of the Unified Patent System (UP/UPC)

The EPO explains that once the unitary effect of a European patent is registered, it will provide unified protection in participating countries where the UPC Agreement is in force at that time (effective in 18 countries as of April 2026).The UPC has exclusive jurisdiction over certain actions, including patent infringement, invalidity (revocation), and injunctions (UPCA Art. 32), and its judgments are enforceable in member states (UPCA Art. 82).

Two Pillars of Portfolio Design

In practice, the strategic approach involves designing a portfolio that combines the following two options based on the characteristics of each case.

Cost and Translation Strategy

EPO Official Fees (Revised as of April 1, 2026)

For a standard "online application with up to 15 claims and up to 35 pages," the minimum official fees are approximately 135 for the filing fee + 1,595 for the search + 720 for designation + 2,010 for examination + 1,135 for grant = 5,595 euros (plus pending annuities).However, since EPO annuity costs increase depending on the number of years until grant (pending period), striking a balance between early grant and responding to amendments and examination is essential for cost management.

Translation Obligations and Three-Tier Management

Translation is managed through the following three tiers.

Regarding post-grant translations, since the translation burden is reduced in countries where the London Agreement applies, the selection of countries based on the scope of rights, market, and litigation prospects significantly affects cost-effectiveness.Unified Patent renewal fees are paid in a single installment, with amounts such as €35 in the second year and €1,175 in the tenth year proposed. For the Unified Patent, the system is designed to require additional translations during the transition period (up to 12 years), so in practice, it is necessary to simultaneously manage both “arranging translation work” and “deadlines for registration of unified effect.”

Strategic Advice

The greatest advantage of the PCT route is that it allows decision-making and cost expenditure to be deferred until the regional phase (European phase), generally for 30 months (31 months for the EPO).While Euro-PCT requires meeting the set of requirements under Rule 159 within 31 months, early processing allows for an accelerated timeline, enabling you to plan “when to proceed with the European phase” in alignment with business events such as product launches, fundraising, or anticipated litigation.

Division applications may be filed while the parent application is pending (Rule 36(1)), the subject matter of the division must not go beyond the disclosure in the parent application at the time of filing (Article 76(1)), and the priority date, etc., is linked to the parent application.Division strategies are effective for (a) addressing unity and search limitations, (b) creating a hierarchical structure of rights by market or embodiment, and (c) recovering claims eliminated during amendments (Art. 123(2)), but success depends on managing the parent application’s pendency (determining the deadline for filing divisions) and strictly ensuring that the “original disclosure” is preserved in the division.

Practical Checklist

Summary: Key Points of European Patent Strategy

The European patent system is a complex framework comprising a two-tier structure—a single grant procedure based on the EPC and country-specific effect after grant—to which the option for central litigation via the UPC, launching in 2023, has been added. The key practical points are summarized as follows.

First, the “substance of the specification at the time of filing” forms the foundation of everything. The three pillars—the prohibition on additions under Art. 123(2), the requirement to demonstrate inventive step under G 2/21, and claim interpretation under G 1/24—all converge practice toward scrutinizing the “quality of disclosure at the time of filing.”

Second, the systematic management of deadlines is key to preventing errors. Deadlines such as the request for examination (six months from the search report), Rule 71(3) (four months—effectively non-extendable), opposition (nine months), and appeal (two months plus four months) should be managed with a clear understanding of their starting points and available remedies.

Third, the decision to utilize the UP or UPC should be made on a portfolio-by-portfolio basis. It is reasonable to combine the two options—choosing the UP if prioritizing broad injunctions and opting out to avoid the risk of central invalidation—based on case value, countries of operation, and the competitive environment.

Fourth, cost optimization lies in the design of translation and country selection. Estimates that incorporate the use of London Agreement countries, the single renewal fee for the unitary patent, and additional translation requirements during the transitional period will determine long-term costs.

Securing and enforcing European patent rights requires a practical strategy based on the interplay between EPC provisions, EPO guidelines, Enlarged Board of Appeal case law, and UPC case law. For each individual case, we recommend that Japanese patent attorneys and European representatives collaborate to evaluate the “depth” of the specification, the “starting point” for deadlines, and “strategic choices” regarding the UPC.