10 June 2021

Filing an opposition as a straw man: the pros and cons

European patents can be opposed by ‘any person’ within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin. The phrase ‘any person’ includes anyone other than the patent proprietor themselves (G 3/93, G 3/97). Even a person listed as an inventor on a particular patent can oppose that patent (T 3/06).

In a recent appeal at the European Patent Office (EPO) (T 1839/18), the patent proprietor argued that the opponent did not have a legitimate interest in the outcome of the opposition and, therefore, the opposition should be found inadmissible. However, the EPO reaffirmed the principle of ‘any person’ oppositions, stating in the decision, among other things, that any person who starts opposition proceedings provides three main contributions to society at large:

            (1) Undeserved monopolies may be revoked or limited to their due scope;

            (2) industrial development is fostered in that the direction of innovation is not led astray by wrongfully granted monopolies; and

            (3) legal certainty is enhanced.

Given that the opponent can be ‘any person’, this allows potential opponents to hide their true identity by filing the opposition as a ‘straw man’. Filing an opposition as a ‘straw man’ can have a number of advantages and disadvantages.

‘Straw man’ opposition advantages

A potential opponent may wish to avoid alerting the patent proprietor to their interest in the patent potential infringement – for example, the potential opponent may wish to avoid bringing their activities to the attention of the proprietor.

Another reason may be to avoid upsetting an amicable relationship with the proprietor – for example, the potential opponent may be a business partner of the patent proprietor or even a licensee of one or more of the proprietor’s patents.

Additionally, a potential opponent may wish to avoid submitting publicly available arguments regarding, for example, particular interpretations of the patent. In this way, a potential opponent may avoid issues arising from prosecution history estoppel because the arguments filed in the opposition would not be attributed to the company behind the ‘straw man’.

‘Straw man’ opposition disadvantages

In one example, a ‘straw man’ opponent requested the opposition proceedings to be accelerated to provide certainty regarding the fate of the opposed patent before the company behind the ‘straw man’ invested large sums of money into an area which potentially infringed the patent claims. The request for acceleration was denied because the ‘straw man’ opponent did not itself have a legitimate interest in the proceedings being dealt with rapidly. As the company behind the ‘straw man’ was not a party to the proceedings, there was found to be no reason why the interests of a third party should be attributed to the ‘straw man’ (T 0872/13).

It appears in this case that the need for accelerated proceedings was greater than the need for anonymity for the company behind the ‘straw man’. If this had been determined before filing the opposition, then the opposition could have been filed in the name of the ‘true opponent’ which would likely have led to the request for acceleration to be allowed.

In another example, a ‘straw man’ opponent filed experimental evidence which allegedly showed that the patent in suit was not sufficiently disclosed. However, the provenance of this evidence was not provided, presumably because it would reveal the company behind the ‘straw man’, and as such the veracity of the evidence could not be assessed (T 0103/15).

This situation might have been avoided, if before the opposition was filed, the opponent identified that experimental evidence was likely needed to have the patent revoked or limited. Then, the opponent could have arranged for the experiments to be conducted by an independent third party whose identity could have been provided without exposing the identity of the company behind the ‘straw man’.


From the above review, it is clear that oppositions filed under a ‘straw man’ can be beneficial to a potential opponent’s business strategy, but that poor planning of the opposition can lead to unintended negative consequences for the opponent. Therefore, whilst it is certainly worth considering filing an opposition as a ‘straw man’ to obtain the advantages above, care should be taken to identify any potential pitfalls ahead of time to allow appropriate action to be taken to avoid the disadvantages.

Conor McGuinness
Technical Assistant