Edwards Lifesciences LLC & Ors v Boston Scientific Scimed Inc

A patent claim requiring a “sac” is not satisfied by every cavity capable of receiving material and forming a seal. In its context, a sac means a bag-like cavity providing a substantial degree of enclosure, although it may contain limited openings.

A party should generally challenge important opposing evidence in cross-examination. The rule is flexible, particularly for expert opinion exchanged over several rounds. Unchallenged expert evidence need not automatically be accepted. On appeal, the decisive question is whether the absence of cross-examination caused unfairness sufficient to undermine the trial judge’s decision.

Two patents concerned fabric seals intended to reduce leakage around transcatheter replacement heart valves. Edwards sought revocation, and Boston counterclaimed for infringement. The Patents Court, in [2017] EWHC 405 (Pat), held patent 254 obvious over the Thornton prior art, but upheld patent 766 and found specified claims infringed.

Edwards appealed against the validity finding on patent 766, arguing that the device found obvious under patent 254 also contained the claimed “sac”. Boston appealed against the invalidity finding on patent 254, contending that the judge could not reject material evidence from its clinical expert when that evidence had not been individually challenged in cross-examination.

1. Both appeals were dismissed. The Patents Court’s conclusions that patent 766 was valid and patent 254 was obvious were upheld.

2. The word “sac” in claim 1 of patent 766 meant a bag-like cavity providing a substantial degree of enclosure. The claim did not encompass every cavity capable of receiving blood or another material and thereby forming a seal. Limited openings were permissible, including an opening allowing blood to enter, provided that the structure retained its bag-like and substantially enclosed character.

3. The Thornton flange did not constitute a sac in its undeployed condition. It was wide open and was better characterised as flange-like or dish-like. Nor did the trial judge’s findings establish that deployment would necessarily create one or more bag-like enclosures. The evidence left the resulting configuration uncertain. Claim 1 of patent 766 was therefore not shown to be obvious over Thornton. It was unnecessary to decide the independent validity of claims 4 and 7.

4. A party should generally challenge important opposing evidence in cross-examination if it intends to submit that the evidence should be rejected. The rule serves fairness to both the witness and the parties, and applies with particular force to direct factual evidence. It is nevertheless flexible. Procedural rules serve justice, and the failure to challenge an expert on every point does not automatically compel acceptance of that expert’s evidence.

5. Where several rounds of expert reports have clearly exposed the competing opinions, the witness has already had an opportunity to respond. The risk of unfairness is consequently reduced. Separate cross-examination of experts from different disciplines is also unnecessary where their evidence genuinely overlaps and no material point lies exclusively within one expert’s field.

6. On appeal, the question is whether the decision not to cross-examine caused unfairness sufficient to undermine the trial judge’s decision. Professor Lutter had seen and could answer the opposing opinion, his central reasoning was challenged, and his evidence overlapped with that of Boston’s engineering expert. The obviousness decision on patent 254 was therefore not unsafe.

1. Court of Appeal (Civil Division): By [2018] EWCA Civ 673, dismissed both Edwards’ appeal concerning patent 766 and Boston’s appeal concerning patent 254.
2. High Court, Patents Court: In [2017] EWHC 405 (Pat), HHJ Hacon held patent 254 obvious over Thornton, but upheld patent 766 and found specified claims infringed.