Gideon Korrell Discusses the Hidden Dangers of Ambiguous Patent Language

Patent drafting often rewards clarity, but it punishes ambiguity even more. In Aortic Innovations LLC v. Edwards Lifesciences Corp., the Federal Circuit delivered a practical reminder: the way you describe an invention can quietly redefine your claims. What appears to be careful wording can later operate as a binding limitation.

Why This Case Matters

At its core, the dispute turned on claim construction. The term “outer frame” became the focal point. While it might sound straightforward, the court found that the patent’s specification had consistently used “outer frame” interchangeably with “self-expanding frame.”

This seemingly harmless drafting habit proved decisive. Once the court adopted that interpretation, the accused product, based on a balloon-expandable design, could not infringe. The case shows how small linguistic patterns can shape the outcome of complex litigation.

As Gideon Korrell often emphasizes, claim construction is less about argument and more about interpretation. Courts study the specification closely, looking for repeated language that signals intent.

The Technology Behind the Dispute

The patents involved devices used in transcatheter aortic valve replacement (TAVR). These devices are inserted into the heart and expanded to replace a damaged valve.

There are two main expansion methods:

• Balloon-expandable frames

• Self-expanding frames

The claims described a system with both an “inner frame” and an “outer frame.” The inner frame was understood to be balloon-expandable. That left the outer frame’s meaning open to interpretation at least initially.

How the Court Interpreted “Outer Frame”

The district court, later affirmed by the Federal Circuit, concluded that “outer frame” meant a self-expanding frame. This was not based on a single sentence, but on a pattern across the specification.

Key factors included:

• Repeated interchangeable use of “outer frame” and “self-expanding frame.”

• Lack of examples showing an outer frame that was not self-expanding

• Descriptions of the invention that treated self-expansion as a standard feature

The court relied on principles from Phillips v. AWH Corp., which prioritize the specification as the primary guide to claim meaning. It also followed the idea that a patentee can act as their own lexicographer even without explicit definitions.

The Risk of Implicit Definitions

One of the most important lessons from this case is the concept of implicit lexicography. This occurs when repeated usage effectively defines a term, even if no formal definition is provided.

In this case:

• The patent never explicitly defined “outer frame”

• But it never used the term differently either

That consistency worked against the patentee. The court treated the repeated pairing of terms as intentional, not stylistic.

As Gideon Korrell has noted in similar contexts, patent drafting is closer to contract writing than storytelling. Variation in wording encouraged in general writing can create unintended legal consequences.

Drafting Pitfalls to Avoid

This decision highlights several practical risks:

1. Overusing Synonyms

Using different terms for the same concept may seem elegant, but in patents, it can imply equivalence.

2. Failing to Show Alternatives

If a feature is optional, the specification should clearly demonstrate alternatives where it is absent.

3. Broad Statements in Summaries

Unqualified descriptions in the summary section can act as de facto definitions of the invention.

4. Inconsistent Strategic Thinking

Writers often focus on readability, but patents require consistency above all else.

Practical Takeaways for Patent Professionals

To reduce risk, consider the following:

• Use consistent terminology for key elements

• Avoid interchangeable phrasing unless equivalence is intended

• Include clear examples of variations and alternatives

• Review the specification as a whole, not just individual sections

These steps can help prevent courts from narrowing claim scope based on unintended patterns.

Conclusion

The ruling in Aortic Innovations underscores a simple but demanding principle: precision matters more than style in patent drafting. What reads smoothly today may become a limitation tomorrow.

For practitioners, the lesson is clear. Every word in a patent carries weight. And as Gideon Korrell often points out, the outcome of litigation is frequently shaped long before it begins during the drafting process itself.