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Transferring burden of proof in sufficiency to the patentee

In the established case law of the Boards of Appeal, each party bears the burden of proof for the facts it alleges. During prosecution, for an insufficiency, novelty or inventive step objection, the burden of proof lies initially with the Examiner (T 578/06). An Examiner may not, for example, simply recite common general knowledge against a claim if the common general knowledge is disputed and the Examiner must instead provide documentary evidence of the common general knowledge.

In previous decisions, disputes of insufficiency before the EPO during opposition, the burden of proof is initially on the side of the party alleging that the patent or application is insufficient (i.e. the opponent). The opponent must provide evidence that, despite making all reasonable efforts, they were unable to put the invention into practice.

EP 2191187 relates to a device and method for renewing buried pipes. A part of the application was directed toward an “adjusting device”, however the adjusting device was not shown in figures and only briefly mentioned once in the application. During opposition, the opponent questioned the feasibility of the adjustment device and how it would be used.

The Board of Appeal considered the question of whether the patent (together with common general knowledge) sufficiently disclosed the adjusting device, and decided such a device would be difficult to construct without inventive skill. The Board reasoned the burden of proof had shifted from the opponent to the patentee because the patentee had failed to provide even one example of an adjustment device as claimed. The patent was therefore revoked for insufficiency.

The legal reasoning in this decision is similar to that of T 63/06. In this case, the Board found that the patentee was relying on a weak presumption that the invention was sufficiently disclosed, and the opponent was successfully able to shift the burden of proof onto the patentee by arguing that the skilled person would have difficult in putting the invention into practice without inventive ingenuity.

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