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For each IP right we offer services covering strategic advice, pre-registration searches, registrations and renewals, oppositions and dispute resolution. We handle work throughout the world, working with local colleagues in over 100 countries.


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Anonymous oppositions – staying undercover at the European Patent Office

11th Jun 2021

In their recent decision (T1839/18), the boards of appeal reaffirmed the legality of straw man oppositions. Although this in itself is not news, we felt it offered a good opportunity to look again at the many advantages of anonymously opposing a European patent. 

European patent oppositions – The basics

The validity of a European patent may be challenged in opposition proceedings before the European Patent Office (EPO) within nine months of grant of the patent.  EPO oppositions are inter partes procedures, involving both the opponent(s) and the patent owner. 

Compared to litigation in the national courts, EPO oppositions provide a cost-effective and efficient way to challenge the validity of a European patent centrally, negating the need to litigate in each individual country in which the European patent is validated.

When opposing a European patent, it is necessary to identify an opponent but the opponent does not have to have standing to oppose – i.e. they do not need to provide a reason for opposing.  As such, it is possible for the named opponent to be instructed by a third party, in what is known as a “straw man” opposition. The legality of straw man oppositions is robustly supported by EPO case law (for example see G3/97, G4/97 and T 1839/18) and the filing of straw man oppositions is a well-established practice at the EPO.

Crucially, a straw man opposition enables a party to challenge the validity of a European patent anonymously, allowing them to keep their identity secret from the patent owner and any other interested parties. This ability to challenge patents anonymously before the EPO provides numerous benefits to a challenging party, and contrasts with the majority of revocation proceedings around the world, which require the identity of the interested party.  

Benefits of filing a straw man opposition

Benefits of filing a straw man opposition include:

  • Reducing the risk of retaliation from the patent owner

Filing a straw man opposition may avoid starting a wider conflict with the patent owner.

It may be the case that the challenging party is infringing, or will infringe, the patent in question but the patent owner is not yet aware of this.  To reduce the risk of the patent owner suspecting infringement, the challenging party may use a straw man opposition to avoid alerting the patent owner to their interest in the patent, while at the same time having a chance to centrally revoke the patent.

In other cases, a challenging party with a patent portfolio of their own may want to file a straw man opposition to reduce the risk of the patent owner filing retaliatory oppositions against their own patents.  A patent owner cannot retaliate if they do not know the identity of the opponent.

  • Avoid damaging a commercial relationship with the patent owner

It is not uncommon for the customer of, or supplier to, a patent owner to want to challenge the validity of a patent while maintaining a commercial relationship with the patent owner.  The patent may, for example, be preventing the party from working with other companies or expanding to other territories.  In such a situation, a straw man opposition enables the opposing party to challenge the patent anonymously thus avoiding any ill-will that is likely to arise from opposing the patent of a commercial partner.

  • Improve a negotiation position with the patent owner

In a similar vein, straw man oppositions are often used to assist a challenging party in license or purchase negotiations with the patent owner.  Openly opposing a patent critical to the negotiations may damage the relationship between the parties, whereas a straw man opposition keeps the strength of the patent in doubt, thus potentially reducing the final price of the deal without souring the negotiations.

  • Freedom from estoppel

A more subtle upside to filing a straw man opposition arises when a challenging party wants to use their own rights, such as an earlier patent, as prior art in opposition proceedings.  A straw man opposition allows them to use their own earlier patent as prior art without assuming the risk that their arguments could be used against them in subsequent proceedings involving their patent.

  • Hide interest in a particular area of technology

In more general terms, a straw man opposition enables a challenging party to hide their interest in a particular technical field from their competitors.  This is often necessary if development is at a very early stage and the challenging party does not want to alert competitors to their activities in this area.

Straw men at video conference (ViCo) hearings

As previously reported by Reddie & Grose, video conference (ViCo) hearings for oppositions are now common place at the EPO.  Opposition hearings were always open to the public but ViCo hearings present additional benefits for a party instructing a straw man opposition because they allow the instructing party to anonymously listen in to the proceedings and engage with their attorneys during the proceedings.  Even with a fake beard and sunglasses it can be difficult to remain anonymous at in person oral proceedings.

How to file a straw man opposition

To file a straw man opposition, it is necessary to find a party willing to be named as the opponent.  To simplify the process, we at Reddie & Grose have our own straw man company, Camulon Ltd, which can act as opponent in your opposition proceedings.

If you would like to discuss filing a straw man opposition, please get in touch with a member of our opposition team.

This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.

James Spencer
Senior Associate
About the author

Adam Rimmer
About the author

Would you like to know more? You can talk to James Spencer who will be able to help. Call +44 (0)20 7242 0901


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