Sara Lee Household & Body Care Ltd v Johnson Wax Ltd

Patent claims receive a purposive construction, but construction cannot turn a conduit into a liquid-permeable closure. A variant falls within the claim only where it has no material effect on how the invention works and that fact would have been obvious to the skilled addressee when the patent was published. The skilled addressee should not need to build and test the variant. The court must balance fair protection for the patentee with reasonable certainty for third parties. Where the claim identifies particular structural features as essential to the invention, an equivalent result will not justify ignoring those features.

Sara Lee alleged that Johnson Wax’s Mark I and Mark II Toilet Duck products infringed claims of a patent for a cleansing and freshening toilet-bowl unit. The products used a bottle, a delivery platform and either a porous pad or a tray. The deputy judge held that neither product infringed, while rejecting the attack on validity. Sara Lee appealed on infringement and Johnson Wax cross-appealed on other matters. The principal issue was whether the products’ shelf-and-hole arrangement constituted a liquid-permeable closure and whether the differences from the claimed apparatus were immaterial variants.

1. Appeal dismissed. The cross-appeal and application to adduce further evidence were dealt with by no order on the cross-appeal; the appellants were ordered to pay the costs of the appeal, cross-appeal and evidence application. Permission to appeal to the House of Lords was refused.
2. Construction was a matter for the court, assisted by evidence explaining technical terms, apparatus, processes and common general knowledge. It could not be delegated to scientific witnesses. Under section 125 of the Patents Act 1977 and the Protocol on the Interpretation of Article 69, the claims had to be construed purposively in the context of the specification, while maintaining fair protection and reasonable certainty.
3. In context, a liquid-permeable closure meant a closure which restricted and diffused liquid movement. The 3 mm hole in the Mark I shelf acted as a conduit. It neither regulated liquid flow nor restricted air bubbles in the manner of the porous closure described in the patent. The shelf was also outside the bottle mouth. These differences were material, and the Mark I did not infringe.
4. The Protocol questions were an aid, not a substitute for construction. The second question concerned what would have been obvious to the skilled addressee at publication. The addressee should not have to construct and test the variant. The evidence did not establish that the relevant differences in Mark I were obviously immaterial.
5. Mark II also did not infringe. Even assuming that its tray was an immaterial variant of a porous pad, that would not have been obvious to the relevant skilled addressee. More fundamentally, the characterising features of claim 1 were absent. The liquid-permeable closure and porous mass were essential requirements of the claimed invention.

• Court of Appeal (Civil Division): The appeal from the decision of Mr David Young QC, sitting as a deputy High Court judge in the Patents Court, was dismissed. Johnson Wax’s cross-appeal was subject to no order.
• Patents Court: The deputy judge held on 8 December 1999 that neither Mark I nor Mark II infringed, and rejected the challenge to patent validity.