Design Patent Infringement: Tests, Damages, and Defenses

Design patent infringement happens when someone makes, uses, sells, or imports a product whose appearance is substantially the same as a patented ornamental design—close enough that an ordinary purchaser could mistake one for the other. A design patent covers only the look of a manufactured item (its shape, its surface decoration, or both), not how it works.¹ Protection runs 15 years from the date the patent is granted.² Because the whole claim of a design patent lives in its drawings, the infringement question is a visual one, and the answer turns on a single legal test.

The Ordinary Observer Test

Courts use one test, and only one. The Supreme Court set it out in 1871 in Gorham Manufacturing Co. v. White: if an ordinary observer, giving the attention a typical purchaser would give, finds two designs substantially the same—similar enough that the resemblance could deceive the observer into buying one thinking it was the other—the later design infringes.³ In 2008, the Federal Circuit confirmed in Egyptian Goddess, Inc. v. Swisa, Inc. that this is the sole standard. Earlier decisions had also required proof that the accused product copied specific “points of novelty” in the patented design; that added requirement is gone.⁴

A few practical points shape how the test actually plays out. The comparison is between the accused product and the patent drawings, not whatever product the patent holder happens to sell. The ordinary observer is not a first-time viewer; the observer is assumed to be familiar with existing designs in the field, which lets them tell what is genuinely new about the patented design from what is common in the category.⁴ And the question is overall visual impression, not a checklist of matching features. Minor differences—a slightly different color, an extra screw on the underside—rarely rescue a product whose dominant look matches the patent.

Defenses That Can Defeat the Claim

Even a close visual match does not end the case. Three defenses come up repeatedly.

Invalidity Based on Prior Art

Prior art—everything publicly known about designs in the field before the patent was filed—does two things at once. It narrows the scope of protection: in a crowded field, small differences between the patent and the accused product carry more weight, because an observer familiar with the crowd is quicker to spot distinctions. And it opens the door to knocking the patent out entirely.

A design patent is invalid if the claimed design was already publicly available before the application’s effective filing date, whether through a publication, public use, or a sale.⁵ Even without an identical earlier design, the patent falls if the differences would have been obvious to a designer working in the field.⁶ Many infringement claims collapse when the accused party finds a product, a catalog illustration, or an expired foreign patent that the examiner missed. That fight does not have to happen at trial; a challenger can file a post-grant review petition at the Patent Trial and Appeal Board, but only within nine months of the patent’s grant date.⁷

Functionality

Design patents protect appearance, not engineering. If a product’s shape is dictated by what it needs to do, that shape is functional and cannot be claimed as an ornamental design.⁸ The question is whether the designer had meaningful alternatives. If the feature could have looked many ways and still worked the same, choosing one look is an ornamental choice and can be protected. If the appearance is the only way to make the product function, it is not. Most products mix the two, and a design patent on a full product does not stop competitors from using the same functional features—only from copying the specific visual package around them.

Patent Exhaustion

Once a patent holder sells a patented product, or authorizes someone else to sell it, the patent rights in that item are exhausted. The buyer can resell it, modify it, or use it as they choose. In Impression Products, Inc. v. Lexmark International, Inc., the Supreme Court held that an authorized sale—domestic or international—exhausts patent rights in the item sold, even if the seller tried to impose post-sale restrictions.⁹ For resellers and refurbishers, this defense is often decisive. The patent holder’s remedy for a broken post-sale restriction would be a breach-of-contract claim, not a patent claim.

What the Patent Holder Can Win

A successful design patent case can produce more than a typical infringement award, because design patents carry a remedy utility patents lost decades ago.

The Infringer’s Total Profit

Anyone who applies a patented design (or a close imitation) to a product for sale, or sells such a product, owes the patent holder the infringer’s total profit from those sales, with a statutory floor of $250.¹⁰ This disgorgement remedy is unique to design patents.

The hardest fight in modern cases is figuring out what “article of manufacture” the profits are calculated on. When a design covers a stand-alone product, the calculation is simple. When it covers only a component of a larger product—the shape of a smartphone screen, for example—the profits from the whole product may vastly exceed what the design contributed. The Supreme Court held in Samsung Electronics Co. v. Apple Inc. that the article of manufacture can be just a component, not necessarily the whole end product.¹¹

Compensatory Damages

Separately, a patent holder can recover damages adequate to compensate for the infringement, and no less than a reasonable royalty for the infringer’s use of the design.¹² The statute bars double recovery of the same profits under both provisions, so patent holders typically pursue whichever calculation yields more.¹⁰

Injunctions

Courts can order an infringer to stop making, selling, or importing the infringing product.¹³ These orders are not automatic; courts apply traditional equity factors, including whether the patent holder faces irreparable harm without the order and whether the public interest supports it. For many patent holders, removing the competing product from the market matters more than any money award.

Blocking Imports Through the ITC

When infringing goods come from overseas, the U.S. International Trade Commission is an additional venue. A design patent holder can file a Section 337 complaint, and if the ITC finds a violation, it can direct U.S. Customs to block the goods at the border through an exclusion order, and issue cease-and-desist orders against specific importers.¹⁴ ITC proceedings often move faster than federal court litigation.

When Damages Get Tripled

Courts can multiply damages up to three times the base amount for willful infringement.¹² In Halo Electronics, Inc. v. Pulse Electronics, Inc., the Supreme Court held that district courts have broad discretion to award enhanced damages but should generally reserve them for egregious cases involving willful misconduct.¹⁵

In practice, willfulness looks like copying a competitor’s patented design after being told about the patent, continuing to sell after receiving a cease-and-desist letter, or launching a product without checking existing design patents in the market. One of the strongest defenses is a written opinion from a patent attorney obtained before launch, concluding either that the patent is invalid or that the product does not infringe. Courts treat that kind of opinion as strong evidence of good faith even if the opinion later turns out to be wrong.

Two Rules That Can Shrink Recovery

Marking

If a patent holder sells products covered by the design patent without marking them with the patent number (or a web address linking to the number), the holder cannot recover damages for infringement unless the infringer had actual notice of the patent and kept infringing anyway. Filing a lawsuit counts as notice, but only damages from that point forward are recoverable.¹⁶ Years of infringement profits can vanish from a damages calculation because of a failure to mark.

The Six-Year Lookback

A patent holder cannot recover damages for any infringement that occurred more than six years before the lawsuit was filed.¹⁷ The rule does not bar the lawsuit itself; it caps how far back the damages can reach. Fraud or concealment by the infringer does not extend it.

If You Receive an Infringement Claim

A cease-and-desist letter or a federal complaint calls for a deliberate response. Ignoring it risks a default judgment that hands the patent holder everything they asked for.

Preserve every document connected to the accused product: design files, prototypes, communications with designers and manufacturers, sales data, and marketing materials. Destroying or altering records after notice of a claim creates separate legal problems and undermines any defense you might raise later.

Then get a patent attorney to evaluate the claim. A thorough evaluation pulls the patent’s file history, studies the drawings, surveys prior art, and compares your product against the patent claim. It also assesses whether the patent itself is vulnerable—whether prior art the examiner missed could invalidate it, or whether the claimed design is driven by function rather than aesthetics. If the patent looks weak and the timing works, a post-grant review at the PTAB may be faster and cheaper than a full trial, but only within nine months of the grant date.⁷

If your attorney concludes that your product does not infringe, or that the patent is likely invalid, getting that conclusion in a formal written opinion is worth the cost. It becomes your best evidence against a willfulness finding if the case reaches trial, potentially keeping damages at the base level rather than tripled.¹² Many design patent disputes end in licensing agreements rather than courtroom judgments, especially once both sides see the cost and uncertainty of litigation.

1
Office of the Law Revision Counsel. 35 USC 171 – Patents for Designs
2
Office of the Law Revision Counsel. 35 USC 173 – Term of Design Patent
3
Justia. Gorham Co. v. White, 81 U.S. 511 (1871)
4
United States Court of Appeals for the Federal Circuit. Egyptian Goddess, Inc. v. Swisa, Inc.
5
Office of the Law Revision Counsel. 35 USC 102 – Conditions for Patentability; Novelty
6
Office of the Law Revision Counsel. 35 USC 103 – Conditions for Patentability; Nonobvious Subject Matter
7
United States Patent and Trademark Office. Post Grant Review
8
United States Patent and Trademark Office. MPEP 1502 – Definition of a Design
9
Supreme Court of the United States. Impression Products, Inc. v. Lexmark International, Inc.
10
Office of the Law Revision Counsel. 35 USC 289 – Additional Remedy for Infringement of Design Patent
11
Justia. Samsung Electronics Co. v. Apple Inc., 580 U.S. ___ (2016)
12
Office of the Law Revision Counsel. 35 USC 284 – Damages
13
Office of the Law Revision Counsel. 35 USC 283 – Injunctions
14
United States International Trade Commission. About Section 337
15
Justia. Halo Electronics, Inc. v. Pulse Electronics, Inc., 579 U.S. ___ (2016)
16
Office of the Law Revision Counsel. 35 U.S. Code 287 – Limitation on Damages and Other Remedies; Marking and Notice
17
Office of the Law Revision Counsel. 35 USC 286 – Time Limitation on Damages