UPC Legal Compass: The Language Regime of the Unified Patent Court

As a court common to multiple EU Member States, the Unified Patent Court (UPC) was required from its inception to address one fundamental question: in what language should proceedings be conducted? The Court’s jurisdiction extends across borders and legal traditions, and its users include litigants, judges, and representatives from all over Europe and beyond. It was therefore inevitable that the drafters of the Agreement on a Unified Patent Court (UPCA) had to reach a compromise between efficiency, fairness, and linguistic diversity. The result is a multilingual system with some flexibilities, where English is emerging as the dominant procedural language.

1. Legal Framework

The UPC’s language regime is governed by Articles 49–51 UPCA and Rules 7, 14, 19-21 and 321-324 of the Rules of Procedure (RoP). It seeks to combine legal certainty with accessibility for parties across jurisdictions.

The resulting system can be summarised as follows:

• Local Divisions: proceedings are conducted in one of the official languages of the host Member State or, if the State so designates, in one of the EPO’s official languages (English, French, or German). Every host State has now designated English as an additional option.
• Regional Divisions: may designate a common language. The Nordic-Baltic Regional Division (Sweden, Estonia, Latvia, Lithuania) has chosen English exclusively.
• Central Division: proceedings are held in the language of the patent as granted by the EPO (English, French, or German).
• Court of Appeal: uses the language of the First Instance unless the parties agree otherwise, or the Court authorises a change under Article 51 UPCA, which also allows special arrangements.

2. Key Case Law Developments

The leading case on the languages regime, and in particular on the interpretation of Art. 49 UPCA, is UPC_CoA_101/2024, 17 April 2024. In this case, the Court of Appeal overturned the Düsseldorf Local Division’s refusal to change the language of proceedings from German to English. It adopted a holistic fairness test, emphasising factors such as the language of the technology and evidence, the nationality or domicile of the parties, their relative size and resources, and any delay caused by a change. The defendant’s position was deemed decisive when interests were balanced.

In the subsequent decision UPC_CoA_354/2024, 18 September 2024, the Court of Appeal further clarified that, in addition to the circumstances stated in the previously mentioned case, the internal working language of the parties, the possibility of internal coordination and of support on technical issues are also relevant circumstances. In this instance, the language of the proceedings were also changed to English, the language of the patent.

Other decisions reaffirmed that fairness, evidence language, and the defendant’s communication environment are central factors in deciding language-change requests.

3. Current Statistics

The most recent official report from the UPC, published in February 2025 and available here, offers insights into the court’s activities, caseload, and significant developments from the time the UPC began operations on 1 June 2023, until the end of 2024.

Although there is no more recent official data, according to the published online trends, the approximate language usage shares are as follows: 

4. Observations & Emerging Principles in Changing the Language of Proceedings

• Holistic Fairness Test – Courts must weigh all relevant circumstances; no rigid standard applies.
• Defendant’s Position Prevails – If the balance is even, the defendant’s preference governs.
• Irrelevant Factors – Counsel’s fluency or judges’ nationality should not influence the decision.
• Timing Flexibility – Requests under Rule 323 may be filed at any procedural stage, provided fairness is respected.
• Substantiation Required – Applicants must show concrete reasons such as translation costs, evidence language, and disparity in resources.
• Post-Hearing Changes – A change may occur even after the oral phase, as it impacts appeal proceedings.

5. Outlook

Two years after its launch, the UPC’s language regime appears reasonably flexible and functional. English has solidified its position as the lingua franca of European patent litigation, and German remains strong, particularly within German local divisions. The balance achieved by Articles 49-51 of the UPCA – which allow for flexibility without eroding national languages – demonstrates the Court’s willingness to transform an inherently political issue into a manageable procedural framework.