Rockwool International A/S v Knauf Insulation Ltd

On an appeal from a patent hearing officer, the court should not interfere with findings on obviousness absent an error of principle, failure to consider material evidence, or reliance on immaterial evidence. The skilled person’s common general knowledge must be distinguished from information obtained by reading prior art. A document cannot make an invention obvious unless it gives the skilled person the relevant teaching; hindsight reasoning is impermissible.

A plausibility objection must be properly pleaded and supported by evidence. Where it is raised informally and late, the hearing officer may consider only whether the proposed amendment is obviously defective on its face. A non-obviousness finding may stand where the prior art does not suggest the claimed technical substitution.

Rockwool appealed against the Comptroller-General’s decision of 28 May 2019 rejecting applications to revoke two Knauf patents concerning formaldehyde-free binders for mineral wool insulation. The patents were considered on the basis of amended claims.

The appeal challenged findings on obviousness, the scope of the broader patent, added matter, plausibility and the adequacy of the hearing officer’s reasons. One ground was not pursued. The central issues were whether the prior art rendered the claimed use of inorganic acid precursors obvious and whether the late plausibility objections were properly before the hearing officer.

1. Appeal dismissed. The court adopted the appellate approach stated in Actavis Group PTC EHF v ICOS Corporation [2019] UKSC 15: interference with a finding of non-obviousness requires an error of principle, failure to consider material evidence, or reliance on immaterial evidence. The court should also avoid undue criticism of an experienced tribunal’s reasons.

2. The hearing officer was entitled to distinguish the skilled person’s common general knowledge from information obtained by reading the prior art. The skilled person knew of the Maillard reaction and its relevance to formaldehyde-free binders, but did not possess the detailed knowledge asserted by Rockwool.

3. The inventive concept was the use of an acid precursor derivable from an inorganic salt in a sugar-based binder, whereas D3 taught an organic acid precursor. D3’s references to inorganic salts concerned chemicals in binders, including corrosion inhibitors, rather than reactants producing the claimed binder. D10 concerned browning reactions in food and added nothing capable of making the claimed substitution obvious. Ground 1 therefore failed.

4. The wider wording of the ‘951 Patent did not alter the result. Rockwool had accepted before the hearing officer that the obviousness arguments for the ‘719 Patent also disposed of the ‘951 Patent. The difference in claim scope had no significance on the facts advanced. Grounds 2 and 3 were untenable.

5. Added matter means new information which the skilled person would obtain from the amended patent but not from the application as filed, applying Nokia Corp v IPCom GmbH & Co KG (No 3) [2012] EWCA Civ 567. The added-matter ground was abandoned, so no formal ruling was made; on the material considered, it would have failed.

6. Plausibility is a relatively low threshold, but an attack ordinarily requires clear pleading and evidence. The late, unpleaded objection could properly be considered only to ensure that the amendments were not obviously implausible. If the hearing officer had treated plausibility as a substantive revocation ground, procedural fairness required Knauf to have an opportunity to respond. Grounds 6 and 7 failed.

7. The hearing officer’s brief reasons on added matter and plausibility were adequate in context because those matters were not properly litigated issues. The hearing officer was merely satisfying himself that the amendments were not obviously improper. The appeal was dismissed.

• High Court (Patents Court): appeal from the Comptroller-General’s decision dated 28 May 2019; appeal dismissed, [2020] EWHC 1068 (Pat).