What Range of Motion Means for Design Patent Rights

The Federal Circuit’s decision in Range of Motion Products, LLC v. Armaid Company Inc., No. 2023-2427 (Fed. Cir. Feb. 2, 2026), provides important guidance for design patent owners and accused infringers regarding functionality, prior art, and claim scope in design patent infringement analyses. In affirming summary judgment of non-infringement, the Federal Circuit concluded that functional considerations may narrow the scope of the protected ornamental design even when the relevant features appear in solid lines in the patent drawings. The decision also illustrates how prior art informs the ordinary observer analysis and confirms that infringement may be resolved as a matter of law when the protected ornamental aspects of the claimed design are sufficiently distinct from the accused design. Chief Judge Moore’s dissent, however, raises significant questions about the proper framing of the ordinary observer test and the role of summary judgment in design patent cases.

Background: The D’155 Design Patent and the Accused Armaid2

Range of Motion Products, LLC (“RoM”) owns U.S. Design Patent No. D802,155 (the “'155 Patent”), titled “Body Massaging Apparatus.” The patent claims “[t]he ornamental design for a body massaging apparatus, as shown and described.” RoM’s Rolflex product embodies the patented design. Armaid Company Inc. (“Armaid”), meanwhile, manufactures and sells the Armaid2, the product accused of infringing the '155 Patent. Armaid had previously manufactured the Armaid1, a massaging apparatus for the arms that embodied U.S. Patent No. 5,792,081, a utility patent titled “Limb Massager.” Below is a side by side comparison of the '155 Patent’s design, the accused device and the prior art.

RoM sued Armaid for infringement of the '155 Patent. In construing the design patent claim, the U.S. District Court for the District of Maine distinguished between functional and ornamental aspects of the patented design. The district court determined that “many, but not all,” of the design features were driven by function and therefore concluded that the overall scope of the design patent claim was narrow. The court subsequently held that no reasonable jury could find the Armaid2 substantially similar to the design claimed in the '155 Patent and granted summary judgment of non-infringement. RoM appealed.

Why This Case Matters for Design Rights

For companies that rely on design patents to protect product appearance, the Range of Motion Products case offers several practical lessons.

First, functionality evidence can narrow enforcement scope. Utility patents, technical evidence, product-development considerations, and marketing materials describing the utility of particular features may affect the scope ultimately afforded to the protected ornamental design. Patent owners should therefore consider how statements made outside the design patent itself may later be used to characterize aspects of claimed features as functionally driven.

Second, solid-line elements are not immune from functionality analysis. Claiming a feature in solid lines does not necessarily mean that every aspect of that feature will receive ornamental protection during infringement analysis. A claimed feature may possess both functional and ornamental characteristics that a court will distinguish when determining claim scope.

Third, designs close to the prior art may receive a correspondingly narrow practical scope. When the claimed design is close to known designs, differences between the claimed and accused products can become particularly significant. Before asserting a design patent, owners should therefore evaluate not only the accused design but also the relevant prior art from the perspective of the hypothetical ordinary observer.

Fourth, summary judgment remains an important defense in design patent litigation. Although infringement is ordinarily a question of fact, the decision confirms that a court may resolve non-infringement at summary judgment when, after properly accounting for functionality and the protected ornamental aspects of the design, the claimed and accused designs are sufficiently distinct as a matter of law.

Finally, the governing doctrine may continue to develop. Chief Judge Moore’s dissent expressly questions the “plainly dissimilar” formulation and its effect on both the ordinary observer analysis and the jury’s role in deciding infringement. Although the majority opinion controls this case, the dissent highlights a doctrinal issue that design patent owners and accused infringers should continue to monitor. Below is a more detailed analysis of the Range of Motion Products case.

Functionality Can Narrow the Scope of the Protected Design

The Federal Circuit began with the established two-part framework for design patent infringement. First, the court construes the claim to determine its meaning and scope. Second, the properly construed claim is compared with the accused design. Where a design includes both functional and non-functional elements, claim construction may identify the non-functional aspects of the design.

This distinction proved central to the appeal. RoM argued that the district court improperly eliminated structural elements of the patented design, focusing in particular on the shape of the device’s arms. The Federal Circuit disagreed and upheld the district court’s determination that the shape of the arms had functional aspects. Importantly, the court did not conclude that the arms disappeared entirely from the infringement analysis. Rather, the court distinguished the functional aspects of those features from their ornamental aspects when determining the scope of the claimed design.

The evidence supporting that conclusion came from several sources. The earlier ’081 utility patent described arms shaped and dimensioned to clamp a limb between massaging members. An affidavit identified aspects of the Rolflex—including the overall “clamshell” appearance and increased curvature of one arm—as enabling the device to massage the entire body. RoM’s own marketing materials also stated that its “clam-shaped roller arms provide significant leverage.” Based on that record, the Federal Circuit agreed that the clamshell shape had a functional role, while recognizing that other characteristics, such as the design’s thick ridged outline, appeared largely ornamental.

For design patent owners, this portion of the decision is particularly significant. Functionality is not evaluated solely by looking at the design patent drawings in isolation. Utility patents, evidence concerning how a product operates, and marketing materials describing the benefits of particular features can all affect how a court understands the scope of the protected ornamental design.

Solid Lines Do Not Resolve the Functionality Question

RoM also argued that the patent drawings established that the shape of the arms was ornamental because those features appeared in solid lines, while disclaimed material appeared in dashed lines. The Federal Circuit rejected that argument. According to the court, accepting RoM’s position would effectively require every feature depicted in solid lines to be treated as wholly ornamental, contrary to precedent recognizing that a design element may possess both functional and ornamental aspects.

The distinction is important for applicants and patent owners. Solid lines identify what is claimed as part of the design, but the use of solid lines does not necessarily prevent a court from considering whether aspects of those claimed features are driven by function. Drawing strategy alone therefore may not insulate a claimed feature from a functionality analysis during enforcement.

The Federal Circuit likewise rejected RoM’s argument that the existence of alternative designs should have prevented further functionality analysis. Although alternative designs can provide important evidence regarding functionality, the court explained that their existence is not a dispositive threshold inquiry that necessarily forecloses consideration of other functionality factors. The court also questioned whether the earlier Armaid1 represented a true alternative design because the Armaid1 and Rolflex had different stated purposes and functional capabilities.

Applying the Ordinary Observer Test

After affirming the district court’s claim construction, the Federal Circuit turned to infringement. Design patent infringement is evaluated under the ordinary observer test: whether, from the perspective of an ordinary observer giving the attention a purchaser ordinarily gives, the claimed and accused designs are substantially the same such that the resemblance would deceive the observer into purchasing one supposing it to be the other. The analysis considers the designs as a whole rather than comparing ornamental features individually. The hypothetical ordinary observer is also presumed to be familiar with the prior art.

RoM argued that the '155 Patent’s design and the Armaid2 were sufficiently similar to require a trial. The Federal Circuit disagreed because, in its view, RoM’s approach gave insufficient effect to claim construction and the distinction between functional and ornamental aspects of the design. Although the district court recognized that the patented design and Armaid2 shared a “broad design concept” and looked similar at a conceptual level, many of those similarities resulted from functional features. Similarity at that general level was therefore insufficient to establish infringement.

Instead, the court focused on differences in the designs’ overall ornamental appearances. Among other things, the district court identified differences in the prominence and configuration of the fixed arm and hinge apparatus, the Armaid2’s more segmented appearance, the relative size of its adjustment slots, and differences in the shape of the hinge apparatus. Taken together, those features resulted in different overall visual impressions. The Federal Circuit therefore affirmed the conclusion that the Armaid2 and the narrow design protected by the '155 Patent were plainly dissimilar.

Prior Art Can Make Smaller Differences More Important

The decision also reinforces the importance of prior art in the infringement analysis. When a patented design is close to the prior art, relatively small differences between the patented and accused designs may assume greater significance to an ordinary observer familiar with that art.

Although the court concluded that the designs were plainly dissimilar without needing to proceed to the three-way comparison involving the prior art, it nevertheless agreed with the district court that comparison with the Armaid1 provided an alternative basis supporting non-infringement. The prior art therefore supplied additional context for evaluating which features would attract the attention of the hypothetical ordinary observer.

This aspect of the decision has practical consequences for design patent enforcement. A patent owner should not evaluate an accused product solely by placing it beside the patented design and identifying apparent similarities. The relevant prior art may materially affect the analysis. Where the patented design represents only a modest visual departure from existing designs, distinctions between the accused product and the patented design that might otherwise appear minor may become important.

The Dissent Questions the “Plainly Dissimilar” Framework

Chief Judge Moore dissented, concluding that a reasonable jury could find the '155 Patent’s design and the Armaid2 substantially similar. Her disagreement extended beyond the facts of the case to what she viewed as a broader problem with the Federal Circuit’s framing of the design patent infringement inquiry.

The dissent argued that asking whether two designs are “plainly dissimilar” or “sufficiently distinct” can improperly shift the focus from the overall similarities between the designs to their individual differences. Chief Judge Moore contrasted that approach with the substantial-similarity inquiry originating in Gorham Co. v. White, under which the effect of the overall design controls. In her view, focusing on differences can cause a decision-maker to give those differences disproportionate importance and lose sight of the designs’ overall similarity.

The dissent was also concerned about resolving such disputes at summary judgment. Chief Judge Moore viewed substantial similarity as a factual issue that, on the record presented, should have been decided by a jury. She would have vacated the judgment and remanded for reconsideration under a framework focused on the overall similarities between the claimed and accused designs.

The dissent does not alter the controlling holding of the majority. It does, however, identify an ongoing doctrinal disagreement concerning how courts should frame the ordinary observer inquiry and when design patent infringement can appropriately be resolved as a matter of law.

Practical Considerations for Stakeholders

Range of Motion Products underscores the importance of evaluating a design patent in the context of the broader evidentiary record. For patent owners, infringement analysis should account not only for visual similarity but also for utility patents, prior art, product literature, and marketing statements that may reveal functional aspects of claimed features. Those materials can influence both claim scope and the ultimate comparison with an accused design.

The decision also has implications for portfolio development. Companies seeking design protection should consider how design patents interact with utility patents and other intellectual property rights covering the same product. Statements emphasizing the functional advantages of a product configuration may support utility patent protection or commercial objectives, but they may also become relevant when a court later assesses the ornamental scope of a related design patent.

For accused infringers, the decision demonstrates the value of developing functionality and prior-art evidence early. Evidence that apparent similarities arise from functional considerations, combined with prior art showing that the patented design occupies a narrow ornamental space, may strengthen a non-infringement defense and, in an appropriate case, support resolution at summary judgment.

Ultimately, Range of Motion Products reinforces that design patent enforcement extends beyond a side-by-side comparison of drawings. The practical scope of a design patent may depend on the interaction among the claimed design, its functional characteristics, the prior art, and the accused product. Patent owners and accused infringers should evaluate those considerations together when developing, asserting, or defending design patent rights.