How to attack a UK patent or application
Reviewed on 6th August 2025
In Europe, the European Patent Convention provides a nine-month “opposition” period following the grant of a European patent in which anyone may try to convince the European Patent Office why the patent shouldn’t have been granted. #
If an opposition is successful, the patent may be revoked with reduced cost and effort relative to national revocation proceedings or court involvement.
There’s no similar period for patents granted by the UK Intellectual Property Office (UKIPO). This means that unless you convince it that an application shouldn’t be granted while it’s still pending, you must start revocation proceedings.
This can make attacking UK patents costly and time-consuming — here’s what you need to know about the process and how you can go about it.
Pre-grant - third-party observations #
While a UK patent application is pending (before it’s granted), anyone may file arguments with the UKIPO as to why it shouldn’t proceed to grant. The arguments must only relate to patentability and an Examiner is obliged to consider them and the associated evidence provided. The UKIPO will acknowledge receipt and notify the applicant of the observations filed, giving them a chance to defend the application.
The third party that filed the observations won’t be informed about any proceedings that may follow. Instead, the progress of the application must be monitored online to determine any effect that the observations have. Further observations may be submitted up until the patent is granted — they may be submitted anonymously and the UKIPO won’t charge a fee for this service.
Post-grant - opinions and the power of the UKIPO #
Before you decide to commit to revocation proceedings once a patent has been granted by the UKIPO, you can ask for an opinion to be issued about whether the patent is valid and/or whether an act would infringe it. While such opinions aren’t binding they can indicate a likelihood of success, should revocation proceedings be brought in the future, and are therefore a useful negotiating tool.
The UKIPO charges a fee of £200 for issuing an opinion. The request is publicly advertised and the patent holder is notified.
If the UKIPO is convinced that a patent is invalid following the issue of a validity opinion, they have the power to revoke the patent themselves, pending the patent holder’s response. Therefore, seeking an opinion on validity can be a cost-effective way of revoking a patent.
Post-grant - revocation #
After grant, proceedings may be brought to have the patent revoked. These can be brought on one or more of the following grounds:
- patentability (such as lack of novelty or inventiveness)
- non-entitlement
- sufficiency of disclosure
- added subject-matter
- unallowable broadening of the scope of protection
Except for on grounds of non-entitlement, anyone may begin revocation proceedings at any time after grant. For cases where entitlement is contested, only a person found to be entitled to the granted patent may invoke this ground and may only do so within two years from the grant date. In any case, and in contrast to third-party observations, the person bringing the proceedings does become a party to them.
Revocation proceedings can be brought before the UKIPO, the Intellectual Property Enterprise Court, or the Patents Court. Where to bring proceedings is initially up to the person seeking revocation, and depends on the complexity of the subject matter, the damages sought and the expense that the person is prepared to bear.
Proceedings before the UKIPO are intended to be quick and inexpensive, while the judges of the Patents Court provide a more rigorous analysis and judgment, as well as greater cost awards. The Intellectual Property Enterprise Court (IPEC) was established to provide a medium between these two. Note that the UKIPO can redirect proceedings that were initially brought to them to the courts of their own volition.
A successfully-revoked patent is revoked ex tunc, meaning it’s deemed to never have been granted. Revocation is therefore a potentially powerful tool when backed by strong arguments and evidence and brought in an appropriately chosen forum.
Need help with cancelling a patent or patent application? Get in touch with us.
