Background
Edgewell Personal Care Brands LLC, the maker of the Playtex brand of infant products, holds a patent covering a diaper disposal system — a device designed to contain and seal dirty diapers to minimize odor. The patent claims describe the structural features of the device, including a “clearance” between certain components. Munchkin, Inc., a competitor in the infant care products market, sells a competing diaper disposal system that Edgewell accused of infringing the patent.
The district court granted Munchkin’s motion for summary judgment of noninfringement, concluding that the accused product did not satisfy the “clearance” limitation of the asserted claims. Edgewell also argued infringement under the doctrine of equivalents, but the district court denied that as well. Edgewell appealed.
The Court’s Holding
The Federal Circuit reversed and remanded. The court reaffirmed a fundamental principle of patent claim construction: apparatus claims must be construed based on what the apparatus is — its physical structure and configuration — not on what it does or how it functions. A court construing a structural claim term cannot redefine it in purely functional terms in a way that departs from its structural meaning.
Applying this principle, the Federal Circuit found that the district court had erred in construing the “clearance” limitation in a way that improperly reduced a structural term to a functional one. Under the correct construction, genuine disputes of material fact existed about whether Munchkin’s product met the “clearance” limitation. Because those disputes needed to be resolved by a factfinder, summary judgment of noninfringement was inappropriate. The court similarly vacated the denial of the doctrine of equivalents claim, which also rested on the flawed claim construction, and remanded the entire infringement question for further proceedings.
Key Takeaways
- Apparatus claims are defined by the physical structure of the claimed device, not by its functional behavior; claim construction of structural terms must preserve their structural meaning.
- A district court errs by construing a structural claim term in functional terms when the claim language and specification describe a physical configuration, not a functional relationship.
- Factual disputes about whether an accused product’s structure meets a structurally construed claim limitation must be resolved by a jury, not on summary judgment.
- The doctrine of equivalents analysis depends on claim construction; an incorrect construction that defeats literal infringement may also improperly prevent a doctrine of equivalents argument from reaching the jury.
Why It Matters
The distinction between structural and functional claim construction is foundational to patent law. Patent claims are “defined” by their scope, and apparatus claims are physically defined: they cover devices that have particular structural features, not just devices that perform particular functions. When courts conflate structure and function in claim construction, they can erroneously narrow (or broaden) claim scope in ways that distort the infringement analysis.
For patent owners seeking to enforce utility patents covering consumer products — particularly in markets like infant care, household goods, or consumer electronics, where competitors frequently design around patents by making minor structural modifications — the Edgewell v. Munchkin decision reinforces that apparatus claims must be read as physical descriptions, and that genuine disputes about structural correspondence are for the jury, not for summary judgment disposition.