Board of Appeal upholds the principle of "any person" opposition in view of the broader public good (T 1839/18)

In contrast to litigation proceedings in national courts, an opposition may be filed against a European patent in the name of a so-called straw man, behind which the identity of the interested party may be hidden.  In a recent Board of Appeal case (T 1839/18), a patentee questioned whether straw man oppositions are in line with the principle that acts performed before the EPO require a legitimate purpose. In its decision, the Board of Appeal presented strong support for the established case law that anyone should be able to file an opposition. The Board cited the broader public interest that invalid patents should be challenged in view of the patent bargain between the state and the patentee. 

Legal Background: Straw man oppositions

Straw Kat
Article 99(1) EPC states that "any person" may file an opposition against a granted patent. The Boards of Appeal have interpreted this as permitting straw man oppositions, by which a party wishing to challenge a patent may hide their true identity from the patentee (G 3/97 and G 4/97). In a straw man [Merpel: or "straw person"?] opposition, the opposition is filed in the name of an uninterested party (often a patent agent) who acts on behalf of the interested company or individual. The only caveat to the general allowability of straw man oppositions is that the opposition does not constitute an abuse of process, e.g. a patentee attempting to oppose their own patent (G 9/93). 

There are many reasons why a party may wish to hide their identity in opposition proceedings. Potential infringers of a granted patent may, for example, file a straw man opposition to avoid alerting the patentee to their activities, or to avoid souring of a commercial relationship. Highly commercially significant oppositions therefore often attract a large number of straw man oppositions, for example in the Broad CRISPR dispute (T 844/18IPKat). Filing a straw man opposition also reduces the risk that your own arguments will be used against you in subsequent litigation. 

No legitimate interest?

The Board of Appeal decision in T 1839/18 considered the admissibility of an opposition filed in the name of a clearly uninterested party (a Spanish garage owner). The patent (EP 2531085), relating to a drinks machine, was maintained in amended form at opposition. The patentee argued on appeal that the Spanish garage owner opponent had no interest what-so-ever in the outcome of the opposition, and that the opposition was therefore inadmissible. 

To support their case, the patentee cited G 1/06. In G 1/06, the Enlarged Board of Appeal (EBA) ruled out the possibility of double patenting on the basis that a patentee could have "no legitimate interest" in owning two patents for the same subject matter (there is currently a pending referral on the issue of double patenting, G4/19 (IPKat)). The patentee argued that the EBA's decision in G 1/06 constituted a general acknowledgement that every act performed before the EPO, including opposition, requires a legitimate interest. 

The Board of Appeal was not convinced by the patentee's argument. Particularly, the Board could not see a reason why the statement in G 1/06 should supersede the established case law on the allowability of straw man oppositions. The Board pointed to the landmark decisions in G 3/97 and G 4/97 that established, as a general principle of public interest, that anyone should be able to challenge a granted patent. 

Abuse of human right to a fair hearing?

The patentee further argued that a system of "any person" opposition contravened Art. 6.1 European Convention of Human Rights (ECHR), according to which everyone is entitled to a fair hearing in civil proceedings. The patentee particularly argued that straw man oppositions denied a patentee the ability to rely on the proceedings by way of estoppel in future infringement proceedings. 

It is a recognised phenomena in patent proceedings that patents are often given a different interpretation in opposition and infringement proceedings, termed the "Angora cat" phenomena after Sir Robin Jacob's comment European Central Bank v DSS [2008] EWCA Civ 192:

Angora Kat
Professor Mario Franzosi likens a patentee to an Angora cat. When validity is challenged, the patentee says his patent is very small: the cat with its fur smoothed down, cuddly and sleepy. But when the patentee goes on the attack, the fur bristles, the cat is twice the size with teeth bared and eyes ablaze.

The patentee posited a situation in which a strawman opponent (who had no real interest in the matter) made some remarks on the interpretation of the patent. If these remarks had been seen to be made by the party with real interest, hidden behind the straw man, the patentee could have made use of the arguments in subsequent litigation against the interested party (e.g. as a counter to the Angora cat phenomena). Consequently, the patentee argued, straw man oppositions run counter to principles of trust and good faith whereby venire contra factum proprium (contradictory behaviour) should be prohibited. 

For the Board of Appeal, the patentee's arguments failed because the question of fairness of estoppel resulting from straw man opposition was one that could only be raised in the relevant subsequent proceedings:

By the simple fact that a statement in possible subsequent proceedings has not yet been cannot contradict a former act or statement...The patentee's case, if any, consequently might be argued in subsequent proceedings, but not in this one.

In a final argument, the patentee pointed to the decision of the Administrative Counsel to permit individuals to pay a reduced appeal fee. The patentee argued that companies may abuse the process by using a straw man individual to file their appeal and thereby take advantage of the lower appeal fee. The Board of Appeal replied rather sardonically that "the Board appreciates the proprietor's concern for office finances" but that "the Boards of Appeal are not the custodians of the EPO's finances and neither are they called upon to question the wisdom of decisions made by the Administrative Council" [Merpel: On which the decision in G3/19 (Pepper) could be said to be a case in point...(IPKat)]. 

The Board of Appeal therefore found the straw man opposition to be admissible. 

"Any person" opposition is a global principle of public interest

In support of their decision, the Board of Appeal in T 1839/18 noted that the EPO's approach to straw man oppositions was not unique. The Board particularly cited a comparative overview of oppositions published by WIPO. The WIPO report noted that in many jurisdictions (e.g. Japan) an opposition may be filed by any person. This corresponds to the broader principle that the validity or invalidity of a patent does not concern a specific individual, but is a matter of broader public interest. 

For good measure, the Board of Appeal also referenced the original English Statute of Monopolies 1623/24, which set out the fundamentals of what has become to be known as the "patent bargain". In the original statue, patents were accepted as burdens to society, whose grant could only be justified by their technical contribution to society. Patents granted without meeting the requirements of patentability, the Board noted, put the patent system's purpose in jeopardy by wrongly preventing competitor research and development. Consequently, according to the Board, any person challenging a patent by way of opposition contributes to society by clearing the register from undeserved monopolies or by adding legal certainty (i.e. where the patent is maintained unamended) (r 2.11). 

The Board of Appeal thus unequivocally found: 

that the current system of allowing any person to have a patent reviewed by way of opposition proceedings regardless of any specific interest is in line with the function of patents to make a technical contribution to society and the public interest in legal certainty and clearing the register from undeserved or undeservedly broad monopolies. Case law of the Enlarged Board of Appeal in this regard is consistent and without contradiction. 

Final thoughts

The decision in T 1839/18 is unsurprising, given the long history of Boards of Appeal case law supporting the principle of "any person" opposition since the landmark decisions on straw man opposition in G 3/97 and G 4/97. The Board of Appeal was clear in its decision that the EBAs case law on straw man oppositions was consistent with later decisions, and was not in contravention of Art. 6 ECHR. More broadly, the reasoning of the Board in the decision is a timely reminder of the legal protections enshrined into patent law and their purpose in providing a patent system operating for the public good. 

Board of Appeal upholds the principle of "any person" opposition in view of the broader public good (T 1839/18) Board of Appeal upholds the principle of "any person" opposition in view of the broader public good (T 1839/18) Reviewed by Rose Hughes on Monday, May 10, 2021 Rating: 5


  1. An opposition by a man of straw has been accepted in G 3/97 as the "true" opponent is subject to the will of the man of straw.
    If the latter withdraws the opposition the “true” opponent cannot suddenly appear, cf. G 4/88 and G 2/04.

    Filing of an opposition by a man of straw has also some drawbacks.
    In T 103/15, the opposition was filed by a man of straw but the OD and the BA did not consider anonymous experimental data.

    When filing an opposition as man of straw, do not request postponement when your “technical expert” cannot be present on the scheduled day!

  2. "In a straw man [Merpel: or "straw person"?] opposition, the opposition is filed in the name of an uninterested party (often a patent agent) who acts on behalf of the interested company or individual."

    Ahh yes, the good old "European Patent Agent" filing oppositions left right and center.

  3. Filing an anonymous opposition by a patent agent is also risky, the uninterested party might be discovered by social engineering. Using public resources like registers or social networks you might find a link between the patent agent and the uninterested person. Even if you use an unknown patent agent, usually suggested by you usual patent agent, there is a risk of discovering a link between both patent agents...

    If anonymity is the real concern you should consider to use a commercial service provider like e.g. This could also solve the problem of anonymous experimental data or? It might not solve the problem of a technical experts attending the oral proceedings.

  4. Wow, there sure seem to be a lot of patent agents around filing oppositions!

    I used to see individual attorneys taking on the role of the strawperson, but I think this has fallen out of favour. I forget exactly why naming an individual was ever seen as preferable to filing in the name of a firm or a made-for-the-purpose shell company. It's a bit morbid, but I always wondered what would happen if that individual died while the opposition was ongoing.


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