Buhler AG v FP Spomax SA

For obviousness in a patent concerning starch milling, the skilled person may be a team comprising process and milling-design engineers with knowledge of dedicated starch production. A prejudice found among bread-flour millers cannot automatically be attributed to starch milling. Common general knowledge must be assessed overall, without starting from an alleged prejudice and asking whether later evidence displaced it.

A patent based on overcoming a technical prejudice need not explain the scientific causation in detail if it identifies the practical departure from the traditional approach and demonstrates that it works. The patent was nevertheless obvious over prior art disclosing successive grinding without intermediate screening. Its amendment to limit the claims to wheat did not add matter.

Buhler sued FP Spomax for infringement of a European patent concerning a milling process and apparatus for producing raw starch material. Infringement was admitted if the patent was valid. Spomax counterclaimed for revocation on grounds of obviousness and added matter.

Buhler abandoned the apparatus claims and accepted revocation of a further patent. The remaining dispute concerned a method claim involving at least two double roller-grinding stages without screening between the successive grindings, followed by screening. The court had to determine the skilled person, the relevant common general knowledge, the inventive concept, the effect of alleged milling prejudice, obviousness over several items of prior art, and whether amendment to limit the claim to wheat added matter.

1. The court approached obviousness using the four-stage formulation in Pozzoli Spa v BDMO SA [2007] FSR 372: identify the skilled person and common general knowledge; identify the inventive concept; identify the differences from the state of the art; and determine whether those differences were obvious.

2. The appropriate skilled person was a team comprising a milling design engineer and a process engineer, with particular knowledge of starch milling. A bread miller, as such, was not part of the team. The team would know both general milling techniques and the requirements and contemporary practices of dedicated starch mills.

3. There was a strong preference among bread-flour millers for screening after every grinding stage. That preference was not automatically part of the common general knowledge applicable to starch milling. The court had to assess all the evidence together, including the different requirements of starch production and existing starch mills using successive grinding without intermediate screening. On that assessment, the alleged prejudice did not materially operate against the relevant skilled person.

4. Even if the prejudice had been established, the patent would not have failed merely because it did not explain the scientific cause of the invention. A sufficient disclosure that the traditional practice could be departed from successfully would identify the inventive contribution. The court treated the guidance in Pozzoli Spa v BDMO SA [2007] FSR 372 accordingly.

5. In the context of the properly identified skilled person, the claim was obvious over the Ellesmere Port disclosure, the Henry Simon “Reform” mill, and the Allis-Chalmers two-pair-high roller mills. Those disclosures made it obvious to try successive grinding without intermediate screening in starch milling and to repeat the arrangement. The Dedrick corn-mill disclosure, considered on its own, involved too great an imaginative step from the claimed wheat starch-flour process.

6. In the context of the patent, “grinding” did not necessarily require fracturing particles into a greater number of smaller particles. It could include gently opening the grain. The amendment limiting the source product to wheat added no subject matter and did not state that wheat possessed a special feature. The added-matter objection therefore failed.

7. The patent should be revoked. The abandoned apparatus claims and the separate 919 patent were also to be revoked as accepted by the parties.