What is validation of a European patent?

A European patent is granted by the European Patent Office (EPO) through a single, centralized examination procedure, but the grant does not automatically create enforceable patent rights in any specific country. To obtain live national rights, the patent owner must complete a process called validation in each country where protection is desired.

Why validation is a separate step

Once the EPO grants a European patent, the patent transforms into a bundle of essentially independent, nationally enforceable, nationally revocable patents rather than remaining a single unified right. Each national patent in that bundle is governed by the domestic law of the country where it has been validated, with infringement litigated in national courts and revocation proceedings running country by country. Protection therefore exists only in countries where the patent owner has actively completed validation; failing to validate in a given country leaves no patent rights there.

Where validation applies

Three categories of countries can be covered through a European patent.

EPC contracting states: The EPC has 40 contracting states as of June 2026, including all 27 EU member states as well as the United Kingdom, Switzerland, Norway, Iceland, Turkey, and other non-EU European nations. Validation in any of these states is governed by that country's national patent law.

Validation states (non-EPC countries with EPO agreements): Morocco (since 2015), Tunisia (since 2017), Cambodia (since 2018), Georgia (since 2024), and Laos (since 2025) have signed validation agreements with the EPO, allowing European patents to take effect in those countries under national law modeled on the EPC.

Extension states: Bosnia and Herzegovina has an extension agreement with the EPO allowing European patents to take effect there when applicants complete the required formalities.

Across all three categories, obtaining protection requires payment of fees and completion of formalities set by each country's national law.

What validation involves

The EPO publishes a mention of grant in the European Patent Bulletin, which triggers the period within which national validation must be completed in each desired state. The deadline varies by country and is governed by each state's national law.

The principal obligations at the national stage are:

National fees. Each national patent office charges its own validation fee, to be paid to the relevant office.

Translations. Where a contracting state requires a translation under Article 65 EPC, that translation must be filed with the national office within the prescribed period. The scope of this obligation varies significantly based on whether the state has joined the London Agreement, described in the next section.

Country-specific requirements should be confirmed with local patent counsel before the deadline, since individual jurisdictions may impose additional formalities.

Translation requirements and the London Agreement

Under Article 65 of the European Patent Convention, a contracting state may require the patent proprietor to supply a translation of the European patent into one of that state's official languages within a prescribed period after grant. The consequence of missing this obligation is severe: if required translations are not filed in time, the patent is deemed void from its inception in that contracting state.

The London Agreement (formally the Agreement on the Application of Article 65 EPC) entered into force on May 1, 2008. In contracting states where the London Agreement applies, the requirement to file a translation has been entirely or partially waived. The scope of the waiver depends on the state's official language: states whose official language is English, French, or German (the EPO's three official languages) dispense entirely with translation requirements, while states with other official languages that have joined the agreement may still require translations of the patent claims only rather than the full specification.

EPC contracting states that have not joined the London Agreement retain the full Article 65 translation requirement. The list of London Agreement parties has grown over time, so current membership must be confirmed for each target country before estimating translation costs.

The Unitary Patent: an alternative for participating EU states

Since June 1, 2023, applicants have had an option that bypasses country-by-country validation for participating EU member states. By requesting unitary effect after grant at the EPO, an applicant obtains a Unitary Patent: a single right providing uniform protection across all participating EU member states through a single registration and a single renewal fee, replacing separate national validation, translation, and renewal payments in those states.

The Unitary Patent covers only the EU member states participating in the system. For non-EU EPC contracting states (such as the United Kingdom, Switzerland, Norway, or Turkey) and for EU states that have not joined the system, separate national validation is still required.

Practical notes for practitioners

• Deadline management. Post-grant validation deadlines vary by country. A single docketed deadline for all jurisdictions is inadequate. Use country-specific deadline calendars and confirm each country's deadline with local counsel before the window closes.
• London Agreement membership changes. A jurisdiction that required full translations at the time of a prior validation may have since acceded to the London Agreement, reducing or eliminating that translation requirement. Verify current membership for each target country before building a translation cost estimate.
• Category distinctions and prosecution requests. EPC contracting states, validation states (Morocco, Tunisia, Cambodia, Georgia, Laos), and extension states (Bosnia and Herzegovina) have different procedural frameworks. Requests to cover validation states and extension states must be made during prosecution of the European application and cannot be added after grant.
• Unitary Patent versus selective national validation. The Unitary Patent provides uniform coverage across participating EU states as a single block. Clients needing protection in only one or two EU states may find selective national validation in those specific states less expensive. The two strategies can be combined: Unitary Patent for the EU bloc plus separate national validation for non-EU EPC states.
• Markets outside the EPO system. The EPC, validation agreements, and extension agreements cover a defined set of countries. For markets not in this system (such as the United States, Japan, China, or India), separate national or regional patent filings are required.