When a joint development partner files alone: what to do first
When a development partner files a patent application without you, the priority date is now fixed and a clock has started. Secure your evidence of contribution first, then check the exact filing details in the relevant register, and challenge entitlement through the deciding forum before any running deadline closes.
What has actually happened
A filing made by one party to a joint development does not settle who owns the invention. It only fixes a date and starts a procedure. Entitlement to an invention made under a joint arrangement is decided under the applicable national law and the development agreement between the parties, not under a single EU-wide rule for this specific question.
The same distinction between "who filed" and "who is entitled" runs through adjacent situations outside patents. A related walkthrough, What to do first in this situation step by-step, deals with ownership of a different kind of result, and the reasoning on evidence and contracts largely carries over.
If the application later proceeds to grant with unitary effect, three later measures start to matter. Regulation (EU) No 1257/2012 sets the framework for the unitary title itself. Council Regulation (EU) No 1260/2012 fixes the translation arrangements attached to it. Disputes over its validity, infringement, or entitlement then sit with the forum created by the Agreement on a Unified Patent Court.
Practical consequence
A filing date is a formal fact, not proof of ownership. The register entry may say one applicant, while the development agreement, correspondence, and lab or engineering records say something else. This gap between the formal record and the underlying right is not unique to patents.
The same tension appears in a different register entirely: When a licence terminates but the token remains and the on-chain record no longer matches who actually holds the right. In both cases, the register is a starting point for a dispute, not the end of one.
For a patent filing, the practical consequence is timing. Once a filing exists, any period for challenging it, opposing it, or asserting a competing entitlement claim begins to run from the filing or priority date shown in the register. That date is fixed by the office or forum handling the application, and it does not wait for you to notice.
What to do first
- Preserve your evidence — the person who holds the technical records collects and dates emails, notebooks, drafts, and any written contribution log before anything is altered or lost.
- Identify the exact filing — IP counsel checks the application number, filing date, named applicant, and named inventors in the relevant national or European register.
- Reread the development agreement — the legal team locates any assignment, licence-back, or entitlement clause that already answers part of the question.
- Fix the running deadline — the patent attorney calculates which period is already running from the date confirmed in step two.
- Choose the route — management decides between a correction of entitlement, a formal opposition, or a negotiated settlement, based on the evidence gathered so far.
- File before the deadline — litigation counsel or the patent attorney submits the chosen notice or claim to the deciding forum while the period is still open.
Who decides
The deciding forum depends on what was actually filed. A national application is decided by the national patent office and, on appeal, by national courts. A classic European patent application is examined centrally but entitlement disputes over it are still decided nationally. A granted patent with unitary effect moves the question to the forum set up under the Agreement on a Unified Patent Court.
| Type of filing | Deciding forum | Governing measure |
|---|---|---|
| National patent application | National patent office, then national courts on appeal | National law and the development agreement |
| Classic European patent (non-unitary) | National courts of each designated state | National law; the development agreement |
| European patent with unitary effect | Forum under the Agreement on a Unified Patent Court | Regulation (EU) No 1257/2012; Council Regulation (EU) No 1260/2012 |
Whichever forum applies, the decision turns on evidence of who conceived the invention, who reduced it to practice, and what the parties agreed in writing before or during the joint development.
If your situation differs
If the filing is still a national application, raise the entitlement question with the national office before it proceeds further; correction is easier before grant than after.
If the filing has already been granted as a classic European patent, the correction of entitlement is pursued in each national court where the patent has effect, one jurisdiction at a time.
If the patent has unitary effect, a single claim before the forum under the Agreement on a Unified Patent Court can cover the participating states in one proceeding, which changes both the cost calculation and the timeline.
Sources and limits
This page answers what to do first and who decides. It does not calculate a deadline for your specific filing, and it does not tell you how many registers or jurisdictions are actually involved in your case — that assessment depends on facts this page cannot see. A parallel resource, Counterparty in Germany and the deadline, shows what a due-diligence report can and cannot establish before a filing decision is made.
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Checked: 4 March 2025. Measures referred to: Regulation (EU) No 1257/2012; Council Regulation (EU) No 1260/2012; Agreement on a Unified Patent Court.
Related situations
FAQ
What is the first step when a joint development partner files alone?
Collect and date your own evidence of contribution, then confirm exactly what was filed and under which type of application in the relevant register.
Which deadline is already running?
The relevant deadline runs from the filing or priority date recorded by the deciding office. It is not extended for a dispute discovered late, so check that date immediately.
Who decides, and on what evidence?
For a national or classic European filing, national patent offices and courts decide, using the development agreement and proof of who conceived and reduced the invention to practice. For a unitary patent, the forum under the Agreement on a Unified Patent Court decides.
If you are facing this now, the fastest useful step is confirming the filing date and the deadline it triggers before deciding anything else.