Defending a patent at the EPO

Your European patent rights are a valuable commercial asset but you risk losing them in an opposition unless a successful defence can be mounted.

That’s where we come in.

We’ll help you develop and implement a strategy that will ensure your European patents are in the best shape to withstand an opposition and/or litigation challenge.


The diagram below sets out the process for defending your patent:


Given the commercial stakes involved in an European Patent Office (EPO) patent opposition, it’s vital you have the right opposition strategy in place from day one.

Before grant

Prepare your patent for the fight

Invest in top-quality patent drafting and produce a patent specification which includes a clear basis for numerous fall-back positions which have potential commercial value. All too often, we see opposition cases where there is no basis for amendment to valid intermediate fall-back positions. This leads to an “all-or-nothing” scenario - either the broad main claim survives, or it falls and there is only basis for a claim too limited to be of any commercial value against competitors.

Avoid the pitfalls of careless prosecution

1. Experience of oppositions informs careful prosecution

Your European patent will be vulnerable to opposition unless the prosecution has been handled with the utmost care.

EPO law and practice regarding basis for amendments is extremely strict. Unallowable amendment is a common ground of invalidity of a European patent, and any amendments made during the pre-grant examination of European applications will come under intense scrutiny during an opposition.

We also see opposition cases where an allowable amendment has been made because the claimed subject matter has clear basis in the application as filed, but it leads to an inadvertent loss of priority because the same subject matter isn’t disclosed in the priority document. Its absence from the priority document is not fixable, but an alternative amendment might have served the same purpose whilst retaining entitlement to priority.

A loss of priority can lead to invalidity based on publications or disclosures that would not otherwise be available as prior art. Hence, the possible impact of any amendment needs to be considered carefully during prosecution.

2. Divide and conquer

It’s always wise to consider making a divisional filing before grant of important cases to provide backup in case the parent patent does not survive an opposition.

Claims of different category and scope can be pursued in such divisionals and may provide an alternative basis for arguments in favour of patentability, whilst still affording a commercially acceptable scope of protection.

If third-party observations have been filed during the examination procedure, it is an indication that the pending claims are of potential relevance to a third party and may indicate an opposition will be filed after the application is granted.

In any event, keep your defence options open by filing one or more divisional applications before grant of your European patent.

After grant

Rapid action is needed

Act as soon as an opposition is filed:

  • Appoint an EPO opposition specialist with a proven track record.
  • Devise your defence strategy.

If you would like to discuss how best to defend one of your patents against an EPO opposition or learn more about our more strategic approach to using EPO oppositions to maximise the value of your innovations, please contact our specialist oppositions team today.