Background
The Toro Company owned U.S. Patent No. 4,694,528 covering a convertible vacuum-blower — an outdoor power tool that can be configured as either a leaf blower or a vacuum. The critical feature of Toro’s design was a removable cover for the blower inlet. The cover included an integrated restriction ring: a ring that, when the cover was attached, reduced the air intake diameter and thereby increased the blower’s output pressure. In Toro’s design, the restriction ring was permanently affixed to and part of the cover — a single, unitary structure.
White Consolidated Industries (WCI Outdoor Products) made a competing vacuum-blower. White’s design used a separate, detachable restriction ring rather than one permanently attached to the cover. When a user wanted blower mode, they would attach the cover and separately attach the restriction ring. The cover and the restriction ring were two discrete, independent pieces.
Toro sued White for patent infringement. The district court initially granted summary judgment for Toro, finding literal infringement. The Federal Circuit reversed in an earlier appeal, holding that because claim 16 required “means for increasing the pressure” permanently affixed to and part of the cover, White’s separately-attached ring did not literally infringe. On remand, Toro pursued infringement under the doctrine of equivalents — arguing that White’s two-piece design was substantially equivalent to its own one-piece design.
The Court’s Holding
The Federal Circuit vacated summary judgment of non-infringement and remanded for trial. Writing for the panel, Judge Rader held that genuine factual disputes remained about whether White’s two-piece design was insubstantially different from Toro’s claimed unitary structure — and therefore whether the doctrine of equivalents reached White’s product.
The court addressed a key tension in equivalents analysis: when claims are expressed in structural terms, courts should not automatically import functional limitations from the specification. The court had previously found that the claim required a unitary structure — cover plus restriction ring in one piece — based on the claim’s structural language. The question was whether splitting that structure into two pieces was a substantial difference or a trivial one. The court found the record was insufficient to resolve that question on summary judgment.
Critically, the court held that the automatic placement advantage of a unitary structure (the ring automatically positions correctly when the user puts on the cover) was inherent in the structure but was not necessarily a “key objective” of the invention that would foreclose equivalents. Whether the two-piece design achieved substantially the same function in substantially the same way to reach the same result required factual development at trial — not a shortcut to summary judgment.
Key Takeaways
- Splitting a claimed unitary structure into separate components does not automatically preclude infringement under the doctrine of equivalents — the substantial equivalence question remains fact-intensive.
- Claims expressed in structural terms should not have functional limitations imported from the specification unless those limitations are expressly claimed or form the essential character of the invention.
- The doctrine of equivalents requires a product-by-product, element-by-element comparison; summary judgment on equivalents is appropriate only when no reasonable jury could find insubstantial differences.
- The structural/functional distinction in claim construction affects — but does not determine — the doctrine of equivalents analysis.
- This case arose on remand from an earlier Federal Circuit decision in Toro v. White (the 1999 panel decision construing the claims), illustrating how claim construction and doctrine of equivalents often generate multiple appellate trips in complex patent cases.
Why It Matters
Toro v. White addresses a common design-around strategy: take a claimed unitary piece and split it into two separate, detachable components. The Federal Circuit’s decision signals that this design-around approach is not automatically immunizing — it may still fall within the doctrine of equivalents if the functional result is the same and the difference is merely one of form. Competitors who attempt to avoid infringement by separating claimed unitary structures must carefully analyze whether their multi-piece design is substantially equivalent to the claimed one-piece design.
The decision also illustrates the limits of summary judgment in patent equivalents cases. Because equivalents analysis is inherently fact-intensive — courts must compare how the accused device functions relative to the claimed element — courts should be cautious about granting summary judgment of non-infringement on doctrine of equivalents grounds when the record contains genuine disputes about how the accused product works.