Occlutech GmbH v AGA Medical Corporation

Factual and Procedural Background

This appeal arises from a judgment by Judge Mann dated 31st July 2009, concerning a patent infringement claim related to European Patent No. (UK) 808 138. The patent covers a collapsible medical device and a method of forming such a device, primarily for occluding blood vessels and other body lumens. The Defendant, Company A, appealed against a declaration of non-infringement in favor of Company B, who manufactures two types of occlusion devices designed to treat atrial septal defects (ASDs) in the heart.

The dispute centers on the interpretation of the term "clamps" used in the patent claims, specifically whether Company B's devices, which secure metal strands by welding at one end rather than clamping at both ends, infringe the patent. The patent specification describes embodiments involving clamps at both ends of a braided metal fabric device, but also discloses alternative methods and fabric types that result in securing strands at only one end.

The judge below rejected the Defendant’s validity challenge based on prior art and found that Company B's devices did not infringe due to differences in the method of securing the strands and the number of clamps used. This appeal challenges that conclusion.

Legal Issues Presented

1. What is the proper construction of the term "clamps" in claims 1 and 16 of the patent, particularly whether it includes securing strands by welding rather than by an external clamping device?
2. Does the phrase "clamps are adapted to clamp the strands at the opposed ends of the device" require clamps at both ends, or can it encompass devices with clamping at only one end?

Arguments of the Parties

Appellant's Arguments (Company A)

• The term "clamp" should be interpreted broadly to include securing the strands by welding or by an external fitting combined with welding.
• The reference to clamps in the claims and specification should be read in light of the entire teaching, including the use of a flat woven fabric inverted to form a pocket, resulting in loose strands at only one end.
• The plural "clamps" in the claims should be understood as a generic term, not strictly requiring multiple clamps at opposed ends.
• The timing of clamping in the method claim (claim 16) suggests clamps may be applied after welding, thus encompassing Company B’s devices.
• The patent file history, although not before the court, indicates the clamp feature was included to avoid prior art and should inform claim construction.

Appellee's Arguments (Company B)

• The ordinary meaning of "clamp" is a device applying external pressure to hold objects together, excluding welding or soldering.
• The patent specification distinguishes clamps from alternative securing methods such as welding or soldering, indicating these are mutually exclusive.
• The claims and description consistently describe devices with clamps at both opposed ends, matching the embodiment of a tubular braid secured by clamps at each end.
• The devices with welding at one end and no clamp at the other do not fall within the scope of the claims as properly construed.
• Reference to the patent prosecution file is inadmissible for construction in this appeal and was not part of the evidence before the judge.

Table of Precedents Cited

Court's Reasoning and Analysis

The court began by emphasizing the principles of purposive construction under Article 69 EPC and the Protocol, as elaborated in Kirin-Amgen and related cases. The skilled addressee is taken to understand the claim language in context, with the description and drawings providing essential interpretative guidance.

The court examined the ordinary meaning of "clamp," supported by dictionary definitions, as an external device applying force to hold parts together. It rejected the appellant's argument that welding or soldering could constitute clamping, noting the patent specification explicitly distinguishes clamps from alternative securing methods like welding or soldering.

The court gave particular weight to paragraphs [0025] and [0026] of the specification, which separately describe clamping by external devices and alternative fixation means. This textual distinction was decisive in construing "clamp" narrowly to exclude welding.

Regarding the phrase "clamps... at the opposed ends of the device," the court found that the claims, supported by Figure 5A and the specification, refer to a tubular braid embodiment requiring clamps at both ends. Although the specification also discloses a flat woven fabric embodiment resulting in loose strands at one end, this teaching is not reflected in the claims before the court.

The court acknowledged the German court's broader interpretation but noted that the German analysis did not consider the possibility that the patentee deliberately limited the claims to the tubular braid embodiment with clamps at both ends. The court rejected the appellant’s submission that the plural "clamps" could encompass a single clamp at one end, reasoning that the claims and specification consistently indicate clamps at both ends.

The court also considered but ultimately discounted the relevance of the patent prosecution file and related correspondence, as this material was not before the court and no Respondent’s Notice was filed to rely on it.

Accordingly, the court upheld the judge’s construction that the claims are limited to devices with clamps at both ends and do not cover Company B’s devices secured by welding at one end only.

Holding and Implications

The court DISMISSED the appeal by Company A.

The effect of this decision is that Company B’s old and new type occlusion devices, which secure the loose ends of their metal strands by welding at one end only, do not infringe the patent claims construed as requiring clamps at both opposed ends. The ruling affirms the importance of precise claim language and the purposive construction approach that respects deliberate limitations chosen by patentees. No broader precedent beyond the specific construction of these claims was established.