Under the ordinary observer test for design patent infringement, a court asks whether an average purchaser, giving the attention a buyer usually gives and familiar with the existing designs in the field, would find the accused product and the patented design substantially the same. The comparison is visual and holistic: overall impression, not a checklist of features. The Supreme Court established the test in 1871, and the Federal Circuit modernized it in 2008 by placing prior art at the center of the analysis and eliminating a separate “point of novelty” requirement.
Where the Test Comes From
The standard traces back to Gorham Manufacturing Co. v. White. The Supreme Court held that if “in the eye of an ordinary observer, giving such attention as a purchaser usually gives, two designs are substantially the same,” and the resemblance would lead someone to buy one believing it was the other, the designs infringe. Two ideas do the work in that sentence. First, the observer is a normal buyer, not a patent lawyer or design expert. Second, the comparison looks for “sameness of effect upon the eye” rather than cataloging small differences a specialist might notice.1Justia U.S. Supreme Court Center. Gorham Company v. White, 81 U.S. 511 (1871)
Two products can differ in small ways and still infringe if the overall visual impact is the same. Products that share some features but look different at a glance will not. The question is whether the resemblance would deceive a regular buyer.
What Gets Compared: Claim Construction First
Before any visual comparison happens, the court must define what the design patent actually claims. Design patents are defined almost entirely by their drawings. The drawings are the claim, and they set the scope of protection.
During claim construction, the court examines the drawings, any written description, and the prosecution history — the record of amendments and arguments made while the patent was being examined. If the applicant narrowed the design to get around prior art, those concessions limit the patent going forward. The court also identifies which features are ornamental and which are functional, because only the ornamental aspects receive protection.2Justia Law. Richardson v. Stanley Works, No. 09-1354 (Fed. Cir. 2010)
Federal patent law only allows protection for a “new, original and ornamental design for an article of manufacture.”3Office of the Law Revision Counsel. 35 USC 171 – Patents for Designs A design patent protects how a product looks, not how it works, and features dictated purely by function fall outside its reach.4United States Patent and Trademark Office. MPEP 1502 – Definition of a Design
The Ordinary Observer, With Prior Art in View
The ordinary observer does not evaluate designs in a vacuum. The Federal Circuit’s 2008 en banc decision in Egyptian Goddess, Inc. v. Swisa, Inc. made clear that the ordinary observer is presumed to be familiar with the existing designs in the field. That context is what separates a genuinely new design from something that already looked like everything else.
The same decision eliminated the older “point of novelty” test, which had required the patent holder to identify and prove copying of specific novel features. The court held that “the ordinary observer test should be the sole test for determining whether a design patent has been infringed.”5United States Court of Appeals for the Federal Circuit. Egyptian Goddess, Inc. v. Swisa, Inc., No. 06-1562 Courts no longer dissect designs into individual novel points. They ask about the overall visual impression, with the prior art providing the backdrop.
The Three-Way Comparison
When the patented design and the accused product are not obviously different, courts use a three-way comparison: the patented design, the accused product, and the closest prior art. The Federal Circuit endorsed this approach in Egyptian Goddess, explaining that “the context in which the claimed and accused designs are compared, i.e., the background prior art, provides such a frame of reference and is therefore often useful in the process of comparison.”5United States Court of Appeals for the Federal Circuit. Egyptian Goddess, Inc. v. Swisa, Inc., No. 06-1562
The result behaves like a sliding scale. If the patented design is a dramatic departure from what came before, small differences between it and the accused product are less likely to defeat infringement. If the patented design lives in a crowded field of similar-looking products, modest differences can be enough to save the accused product. The controlling question is whether the accused product looks more like the patent or more like the prior art.
Who Introduces the Prior Art
The accused infringer bears the burden of putting relevant prior art in front of the court. The logic is practical: the defendant is the one arguing that the patented design is not much of a leap beyond what already existed. If no prior art is introduced, the comparison proceeds without it and the patent gets its broadest possible reading.
Functional Features Get Filtered, Not Dissected
Similarities that arise purely from shared functional requirements do not support infringement. If a particular shape exists because it is the only way to make the product work, that shape is functional and falls outside design patent protection.
The Federal Circuit has instructed courts to “factor out the functional aspects of various design elements” during claim construction, while cautioning that “discounting of functional elements must not convert the overall infringement test to an element-by-element comparison.”2Justia Law. Richardson v. Stanley Works, No. 09-1354 (Fed. Cir. 2010) Functional features get less weight, but the infringement analysis still looks at the design as a whole. The test stays holistic.
Whether a feature is functional turns on whether the design is essential to how the product works or whether alternative designs could achieve the same function. A grip shape driven by ergonomics is functional. A decorative texture on that same grip, unrelated to grip performance, is ornamental. When a design mixes the two, the patent is valid, but its protection extends only to the ornamental aspects.2Justia Law. Richardson v. Stanley Works, No. 09-1354 (Fed. Cir. 2010)
Attacks on the Patent Itself
Accused infringers rarely limit themselves to arguing “our product looks different.” Two attacks on the patent’s validity often run parallel to the ordinary observer analysis and can end an infringement case before the visual comparison controls the outcome.
Lack of Novelty
A design patent is invalid if the same design was already publicly known before the filing date. No patent may issue if the claimed design was already “patented, described in a printed publication, or in public use, on sale, or otherwise available to the public” beforehand.6Office of the Law Revision Counsel. 35 U.S. Code 102 – Conditions for Patentability; Novelty A single prior art reference showing the same overall design can kill the patent. Designers get a one-year grace period for their own public disclosures before filing, but third-party disclosures before the filing date count against them.
Obviousness
Even without a single matching reference, a design patent can be invalidated if the design would have been obvious to an ordinary designer in the field.7United States Patent and Trademark Office. MPEP 2141 – Examination Guidelines for Determining Obviousness Under 35 U.S.C. 103 The obviousness standard changed significantly in 2024. In LKQ Corp. v. GM Global Technology Operations, the Federal Circuit sitting en banc overruled the older Rosen-Durling test, which had required a “primary reference” that was “basically the same” as the patented design. The court replaced it with the more flexible Graham factors already used for utility patents: the scope of the prior art, the differences between the prior art and the claimed design, the level of skill in the field, and secondary considerations like commercial success.8United States Court of Appeals for the Federal Circuit. LKQ Corp. v. GM Global Technology Operations LLC, No. 21-2348 Defendants no longer need to find a nearly identical starting-point reference, which makes obviousness challenges easier to bring.
How the Pieces Fit Together
Read as one process, the analysis moves through predictable stages. The court construes the claim from the drawings and filters out functional elements. The patent holder puts the patented design next to the accused product. The accused infringer brings in the closest prior art. The court, standing in the shoes of an ordinary purchaser familiar with that prior art, decides whether the two designs are substantially the same in overall visual impression. If yes, the accused product infringes. If the accused product looks closer to the prior art than to the patent, it does not.