Is the Scope of a Patent’s Coverage Determined by Its Claims, Or by Its Specification?

Top Patent Judges Disagree

 

By Jakub Michna, a member of our Patent Practice Group

 

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recent decision by the Federal Circuit—the court that hears appeals from all patent cases—highlights the court’s deep division over the role that the specification of a patent plays in claim construction.  While the majority opinion confirms that it is the claims of the patent that govern the scope of protection to which an invention is entitled, the dissent argues that the specification should play a more meaningful role.

(The specification of a utility patent describes the invention, often by highlighting its advantages over existing technology.  This is invariably followed by the claims, which define what the patent “covers.”)

Anyone submitting a patent application should be mindful of the potential implications of this debate.  Through comprehensive drafting, an applicant can navigate the rift within the Federal Circuit.

Arlington Industries, Inc. v. Bridgeport Fittings, Inc. involves a device for connecting electrical cables to junction boxes.  In the past, such electrical connectors used a threaded lock nut to connect the cable to the junction box.  The problem with this configuration is that the installer needed two hands to make the connection, one hand to hold the junction box and the other to thread the lock nut.

Arlington’s patent disclosed a solution to this problem—an electrical connector with a “circular spring metal adaptor” used to snap the electrical cable into the junction box.

The trial judge ruled that Bridgeport’s Whipper-Snapper product line did not infringe claim 8 of the patent, chiefly because he construed the term “circular spring metal adaptor” in that claim to require a split.  The judge reasoned that, without the split, the adaptor could not spring when being inserted into the junction box.  Since Bridgeport’s adaptor did not include a split, it did not infringe the claim.

On appeal, the Federal Circuit found fault with the claim construction and overruled the judge’s holding.  The court pointed out that claim 8 did not require a split limitation and that the district court improperly imported this limitation from the specification into the claim.  The court reinforced the conclusion it had reached in the well-known Phillips v. AWH Corp. case from 2005: “It is a ‘bedrock principle’ of patent law that the ‘claims of a patent define the invention to which the patentee is entitled the right to exclude.’”

The court explained that, while claim 1 of Arlington’s patent requires a “spring metal adaptor being less than a complete circle,” claim 8 omits this limitation.  This distinction tells us that, unlike the adaptor of claim 1, the spring metal adaptor of claim 8 can be either a complete circle or an incomplete circle, i.e., an adaptor with a split or without a split.

In dissent, Judge Lourie contended that the specification does not support such a broad interpretation of the claim.  In his view, the “specification is the heart of the patent” and “you should get what you disclose.”  In support of his position, Judge Lourie noted that no drawing or disclosure appears in the specification in which adaptors consist of a complete circle.  Given this narrow disclosure, the inventors never contemplated that their invention included spring metal adaptors without a split.

Judge Lourie takes a reasonable approach—up to a point.  It seems fair that the scope of patent protection should not extend to embodiments and permutations that the inventors never contemplated.  From the perspective of potential infringers, many times the alleged infringing permutation is the novel design-around that they thought avoided the scope of a patentee’s claim.

Nonetheless, the dissent’s interpretation of the law would overburden patent applicants, who cannot be expected to foresee all possible embodiments and permutations of their invention.  This is especially true with respect to permutations that are based on not-yet-developed technologies.

Furthermore, patent drafters would not know when to stop describing the invention.  If a claim limitation requires a metal material, should the specification provide each metal in the periodic table as an example?  Or is a listing of copper, aluminum and gold sufficient?

This case emphasizes the importance of disclosing and describing multiple embodiments of the invention within the specification.  Patent attorneys should ask inventors about other ways in which their invention can be practiced.  In this case, the attorneys might have asked whether the metal adaptor could have been made from other materials, and whether it required a split.

Under both the majority and dissenting interpretations of the law, providing multiple embodiments and permutations in the specification expands the scope of the claims.  Nothing makes this clearer than a subtle distinction made by Judge Lourie.

Arlington had actually asserted two patents against Bridgeport in this litigation. The term “spring steel adaptor” also appears in the second patent.  As with the first patent, the trial judge construed that term to require a split and thus found no infringement. And, again, as with the first patent, the Federal Circuit overruled the lower court’s holding and its claim construction.

The difference was that, regarding the second patent, Judge Lourie joined the majority. He reasoned that the specification in the second patent showed both an embodiment with a split and without a split and, therefore, the term “spring steel adaptor” could not be limited to only an adaptor with a split.

The Federal Circuit’s division over the first Arlington patent suggests that the role of the specification in claim construction is not yet settled law.  But this rift should not change the patent applicant’s approach to specification drafting.  Under either interpretation, disclosing and describing multiple embodiments of the invention will make courts far more comfortable in extending the breadth of the claims.