When a patent is offered to you for sale: what to do first
Before you agree to anything, confirm three things: who legally owns the patent today, whether any licence, security interest, or pending dispute already limits it, and whether the patent carries unitary effect or sits inside the Unified Patent Court system. Skipping this order turns a purchase into an unpriced liability.
The legal basis for checking before you buy
If the patent in question is a European patent with unitary effect, its scope is set by Regulation (EU) No 1257/2012, and the translation rules that support it sit in Council Regulation (EU) No 1260/2012. Litigation over that same patent, including any validity challenge, falls to the courts created by the Agreement on a Unified Patent Court, unless an opt-out was filed before the transitional window closed. A prior customs enforcement action against the same right, if any, would have run under Regulation (EU) No 608/2013.
A related risk shows up when a reorganisation moves the inventors without moving the rights: What to do first in this situation and the chain of title needs its own check.
What changes once you sign
The Unified Patent Court's transitional period allows opt-outs only within a fixed window. Once that window closes, the patent falls under the court's jurisdiction by default. Buying without checking the opt-out register means inheriting whichever forum applies at the moment of transfer, not the one you assumed. A recorded licence or security interest survives the sale unless the assignment expressly releases it.
What to do first
- Pull the current register entry yourself and compare it against the seller's summary.
- Ask your patent counsel to check for recorded licences, security interests, or pending oppositions against the same right. Some licences are never recorded at all: When a token claims to carry a licence and it fails to hold up, the cost falls on whoever bought the underlying patent.
- Confirm whether the patent has unitary effect and, if so, whether an opt-out from the Unified Patent Court was filed before the deadline.
- Have counsel review any prior customs enforcement action tied to the right, since it shows how the seller has used it.
- Put an ownership warranty and a clear forum clause for future disputes into the assignment agreement before signing.
- Record the transfer with the relevant register once the assignment is signed.
Who decides, and on what evidence
The relevant patent register decides who counts as owner, based on the assignment document filed with it. Disputes about the validity or infringement of a unitary patent go to the Unified Patent Court, unless an opt-out already moved the case elsewhere. Disputes about a classic national patent stay with the office and courts that granted it in the first place.
Common branches
If the patent has unitary effect and no opt-out was filed, expect any future dispute to run through the procedure set out in the Agreement on a Unified Patent Court. If a competitor has already opposed the patent, or its validity is being tested elsewhere, buying it means buying that fight, not avoiding it. If the seller mentions a past customs seizure carried out under Regulation (EU) No 608/2013, treat that as evidence of enforcement history, not as proof that the patent is valid.
Cost factors and turnaround
What a patent purchase review costs depends on how many registers and jurisdictions are involved, not on a fixed fee list.
| Factor | What it changes |
|---|---|
| Number of registers to check | Time needed to confirm chain of title |
| Whether unitary effect applies | Whether Unified Patent Court exposure must be assessed |
| Pending opposition or litigation | Whether the review becomes a dispute review |
| Cross-border seller | Whether a counterparty check is added |
A partner responds with an initial view within minutes during business hours. A firm price for the review follows within one business day.
How the file is organised
Each purchase review is built as a single file: register extracts, licence and security searches, and the opt-out check, kept together so nothing gets checked twice or missed. Where the register that matters sits outside our home jurisdictions, the check is carried out through local delivery partners: see Subprocessors, including local delivery partners in detail for how that work is assigned and supervised.
Sources and limits
This page tells you the order of checks and who decides on a dispute; it does not replace a full assignment review, and it does not price one. If the seller is based outside the EU, a structured counterparty check adds verification that a patent register alone cannot provide: see Counterparty in United Arab Emirates step by step for how that report is built.
Checked: 4 March 2025. Sources: Regulation (EU) No 608/2013; Regulation (EU) No 1257/2012; Council Regulation (EU) No 1260/2012; Agreement on a Unified Patent Court.
Related publications
A related situation, where a standard body claims your patent is essential to a standard, follows a different check order: A standard body claims your patent is essential patent covers what to verify first there.
FAQ
What is the first step when a patent is offered to you for sale?
Pull the current register entry yourself, before you rely on any summary the seller provides.
Which deadline is already running?
If the patent has unitary effect, the window to file an opt-out from the Unified Patent Court runs on its own clock, independent of your negotiation.
Who decides, and on what evidence?
The register decides ownership from the filed assignment. Validity and infringement disputes for a unitary patent go to the Unified Patent Court, based on the case file it receives.
Send us the patent number and the draft assignment. A partner replies within minutes during business hours, and a firm price for the review follows within one business day.