Stretchline Intellectual Properties Ltd v H&M Hennes & Mauritz Ltd

Patent claims are construed through the eyes of the skilled person, by reading the claim and specification as a whole in light of common general knowledge. A penetration barrier need not be a continuous membrane. In the appropriate technical context, it may be a composite structure formed when fusible yarn bonds with other yarns and increases resistance to penetration. Deliberate claim limitations must retain meaning, but the word barrier does not automatically impose a separate, continuous layer. A construction should not be rejected merely because it may make a patent vulnerable to obviousness over common general knowledge. That consequence is materially weaker than a construction which makes the claim read directly on specifically acknowledged prior art.

Stretchline sued H&M for breach of a settlement agreement under which H&M agreed not to deal in products falling within the claims of a patent for tubular fabric. The dispute concerned claim 1, which required fusible yarn to be arranged so that it was capable of forming a penetration barrier.

H&M contended that this required an identifiable, substantially continuous layer or lining. Stretchline argued that bonding between the fusible yarn and surrounding fibres was sufficient. H&M’s invalidity defence and counterclaim had been struck out because the settlement agreement precluded a validity challenge, a decision confirmed on appeal in [2015] EWCA Civ 516. Henry Carr J adopted Stretchline’s construction and found breach in [2015] EWHC 3298 (Pat). H&M appealed on construction and on the alleged consequences for validity.

Appeal dismissed. Lord Justice Floyd gave the substantive judgment and Lord Justice McCombe agreed. The Court of Appeal upheld the construction of claim 1 adopted by Henry Carr J.

1. Patent construction requires the court to determine what the skilled person would understand the patentee to mean by the language of the claim. The specification must be read as a whole and with the benefit of common general knowledge, following the approach identified in Kirin-Amgen and summarised in Virgin Atlantic: [2005] RPC 9; [2010] RPC 8.
2. The claim language was not so clear that it resolved the dispute without reference to the specification. Read in context, the skilled person would not understand the patent to require a continuous discrete layer. The specification’s references to an inner lining, spreading, coating and adherence were consistent with fusible yarn bonding other fibres within the fabric.
3. The word barrier retained legal and technical content. It could describe a composite structure formed by a combination of yarns and points of adhesion. The claim required the fusible yarn to cause or trigger a penetration barrier, but did not require an absolute barrier. It was sufficient that the fabric had greater resistance to penetration than conventional tubular fabric.
4. The court distinguished between common general knowledge and conclusions reached by reading the patent in light of that knowledge. It was open to the judge to find that a continuous layer in woven fabric would require about 50% fusible yarn and was not practical in the claimed context. That did not establish that such a layer was impossible in all circumstances.
5. The possibility that a construction might expose the patent to an obviousness attack based on common general knowledge was a substantially weaker reason for rejecting it than the example in Beloit, where a construction would read directly on specifically acknowledged prior art: [1995] RPC 255. The principle against a foolish construction, discussed in Electric and Musical Industries, did not require rejection of Stretchline’s construction: (1936) 56 RPC 23. The evidence did not establish that using fusible yarn to increase penetration resistance in tubular fabrics was common general knowledge. The appeal was therefore dismissed.

• Court of Appeal (Civil Division): In [2017] EWCA Civ 199, the court dismissed H&M’s appeal and upheld the construction and breach finding.
• High Court of Justice, Chancery Division, Patents Court: Henry Carr J found that H&M had breached the settlement agreement and construed claim 1 in favour of Stretchline in [2015] EWHC 3298 (Pat).
• Earlier appellate stage: H&M’s invalidity defence and counterclaim had been struck out by Sales J because the settlement agreement precluded a validity challenge; that decision was confirmed by the Court of Appeal in [2015] EWCA Civ 516. Stretchline subsequently discontinued its infringement claim.