Watch your words
Patent infringement case fails because of redefined claim term
If there’s ever a time to be careful about how you phrase things, it’s when you’re drafting a patent. One patent holder recently learned the hard way that words used in a specification can end up redefining ostensibly clear patent claim terms — and limiting the patent protection as a result.
Heart of the matter
Aortic Innovations LLC holds a patent for a device for transcatheter aortic valve replacement. The specification discloses two types of devices, including a transcatheter valve. A patent claim relating to the valve describes an assembly comprising an “outer frame” and an “inner frame.” The specification also discloses two types of embodiments.
Aortic sued Edwards Lifesciences Corp. for infringement. In court, the parties disputed the meaning of the term “outer frame.” Aortic argued the term should be given its plain and ordinary meaning of “positioned outside”; Edwards contended it should be interpreted to mean a “self-expanding frame” positioned outside the inner frame.
The trial court determined that the patentee had acted as his own “lexicographer” and redefined the term to be a self-expanding frame. It then entered a judgment of noninfringement because Edwards’ allegedly infringing valve didn’t include a frame.
Lexicography lesson
Aortic appealed the finding of noninfringement to the U.S. Court of Appeals for the Federal Circuit, challenging the lower court’s interpretation of “outer frame.” It claimed that the court improperly excluded the term “outer” from the claim and improperly added a “self-expanding” limitation that wasn’t present in the claim language.
The appellate court began by noting that a patentee can choose to use a broad term in a patent claim and expect to obtain protection for the full scope of the term’s plain and ordinary meaning. But a patentee may narrow that protection by clearly redefining the term — what’s referred to as lexicography.
The standard for this exception, the court said, is exacting. To act as one’s own lexicographer, a patentee must clearly set forth a definition other than the claim term’s plain and ordinary meaning.
That said, an explicit redefinition isn’t necessary. The specification can redefine claim terms by implication so that the meaning may be found in or ascertained by a reading of the patent documents. Such an implied redefinition must be so clear that someone skilled in the relevant field (a “skilled artisan”) would understand that it equates to an explicit redefinition. The court also explained that the consistent and clear, interchangeable use of two terms in a patent can result in a definition that equates the two terms.
Lexicography blocks asserted meaning
Turning to the patent at issue, the Federal Circuit found plenty of evidence in the specification that the claimed term “outer frame” did indeed mean a “self-expanding frame.” For example, the specification referred to the structures in both embodiments as an “outer frame,” a “self-expanding frame” and a “self-expanding outer frame” several times. According to the court, this clearly indicated that the structures were outer frames that must self-expand.
The specification also consistently indicated that the claim’s “outer frame” was a “self-expanding frame.” Its summary section stated that the patent discloses a transcatheter valve that “includes a frame component having a balloon-expandable frame … and a self-expanding frame secured” to that frame.
Finally, the court pointed out that the specification repeatedly states that, in other embodiments, the self-expanding structures disclosed in the two embodiments may differ in features. It doesn’t, however, indicate that the self-expanding nature of the structures is absent or modified in other embodiments.
The appeals court therefore concluded that the specification clearly and consistently conveyed that the self-expanding nature — and limitation — is present in all embodiments of those devices. And a skilled artisan reading the patent would understand that the very character of a transcatheter valve requires the limitation to be a part of every embodiment of it.
Don’t get beat
You might think the meaning of a claim term is apparent, but a court could disagree. Carefully draft your patent applications to avoid costly missteps.
Sidebar: “Disavowal” can change a claim term’s meaning, too
A patentee’s lexicography (see main article) isn’t the only exception whereby a broad patent claim term isn’t given its “plain and ordinary” meaning. A patentee can also disavow claim scope.
When a patent specification makes clear that the invention doesn’t include a particular feature, the feature is treated as outside the reach of the protected patent claims. That’s the case even if the claim language — without reference to the specification — could be considered broad enough to cover the feature.
The patentee can demonstrate its intent to deviate from the ordinary meaning of a claim term by including in the specification expressions of manifest exclusion or restriction. Mere criticism of a particular embodiment encompassed in the ordinary meaning of a claim term doesn’t constitute clear disavowal. Nor is it enough that the only embodiments contain a particular limitation. Rather, a skilled artisan would have to read the specification and conclude that the applicant has clearly disavowed claim scope.
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