Mark R. HOOP and Lisa J. Hoop, Plaintiffs-Appellants, v. Jeffrey W. HOOP, Stephen E. Hoop, and Hoopsters Accessories, Inc., Defendants-Appellees, 279 F.3d 1004

MAYER, Chief Judge. Mark R. and Lisa J. Hoop appeal the preliminary injunction entered by the United States District Court for the Southern District of Ohio enjoining them from acts which would constitute infringement of Jeffrey W. and Stephen E. Hoop’s U.S. Design Patent No. 428,831. Hoop v. Hoop, No. C-1-00-869 (S.D.Ohio Feb. 28, 2001). Because the district court did not abuse its discretion in determining that Jeffrey and Stephen Hoop would likely succeed in sustaining the validity of then-patent, we affirm.

Background In 1998, Jeffrey and Stephen Hoop (“Hoop brothers”) conceived of a pair of eagle-shaped motorcycle fairing guards. Fairings are clear glass or plastic structures mounted above motorcycle handlebars to reduce wind drag. The eagle-shaped guards attach to the fairings to prevent damage to the fairings if the motorcycle tips over.

The Hoop brothers created sketches of the eagle design. (See figures 1 and 2, below.) Lacking drawing and casting expertise, they hired Lisa Hoop, a graphic designer, and Mark Hoop (their cousin and Lisa’s ex-husband), a metal die caster, (“Mark and Lisa”) to create detailed drawings and three-dimensional models for a patent application. Mark and Lisa signed nondisclosure agreements and prepared sketches and molds. (See figure 3, below.) In November of 1999, the Hoop brothers applied for a design patent.

After discussions over a manufacturing agreement between the parties failed, in March of 2000, Mark and Lisa also applied for a design patent, using the same drawings they had prepared for the Hoop brothers. The Hoop brothers’ patent issued on August 1, 2000, as U.S. Design Patent No. 428,831, and Mark and Lisa’s identical patent issued on September 26, 2000, as U.S. Design Patent No. 431,211. In October of 2000, the Hoop brothers asked to have Mark and Lisa’s patent reexamined. During reexamination, the examiner rejected Mark and Lisa’s patent as anticipated by the Hoop brothers’ patent.

Mark and Lisa filed suit in the district court to invalidate the Hoop brothers’ patent, and asserted infringement, unfair competition, and tor-tious interference with prospective economic advantage. The Hoop brothers counterclaimed and moved to enjoin Mark and Lisa from making, using, selling, or offering for sale, any motorcycle fairing guard containing the design in their patent. The district court found that the Hoop brothers were the true inventors, and therefore held that they would likely succeed in sustaining the validity of their patent, and that Mark and Lisa were likely infringing.

The court also held that the Hoop brothers had shown they would suffer irreparable injury absent an injunction. And it reasoned that although a preliminary injunction may cause harm to Mark and Lisa, the public interest favored protection of the patent. The court granted the Hoop brothers’ motion for a preliminary injunction. Mark and Lisa appeal. Discussion Under the patent laws, the district court has discretion to grant a preliminary injunction it deems reasonable. 35 U.S.C. § 283 (1994).

We will affirm unless we find it to be an abuse of discretion, based upon an error of law, or a serious misjudgment of the evidence. Nutrition 21 v. United States, 930 F.2d 867, 869, 18 USPQ2d 1347, 1349 (Fed.Cir.1991). As the moving party, the Hoop brothers bore the burden of establishing their right to a preliminary injunction based upon four factors: “(1) a reasonable likelihood of success on the merits; (2) irreparable harm if the injunction were not granted; (3) the balance of the hardships^] and (4) the impact of the injunction on the public interest.” Purdue Pharma L.P. v.

Boehringer Ingelheim GmbH, 237 F.3d 1359, 1363, 57 USPQ2d 1647, 1649 (Fed.Cir.2001) (citing Polymer Techs. v. Bridwell, 103 F.3d 970, 973, 41 USPQ2d 1185, 1188 (Fed.Cir.1996)). Mark and Lisa challenge only the likelihood of success prong. The question here is whether the refinements made by Mark and Lisa rise to the level of inventorship, so as to displace the Hoop brothers as patentees. Mark and Lisa argue that they are the true inventors because they perfected the original design by adding detail to the design sketches and creating the three-dimensional molds.

Accordingly, they assert that the trial court erred in finding the Hoop brothers likely to succeed in sustaining the validity of their patent. We do not agree. Design patents may be obtained by “[w]hoever invents any new, original and ornamental design for an

article of manufacture.” 35 U.S.C. § 171 (1994). We apply the same standard of inventor-ship to design patents that we require for utility patents. In re Rousso, 42 C.C.P.A. 910, 222 F.2d 729, 731, 106 USPQ 99, 101 (CCPA 1955) (rejecting the assertion that a lesser standard of invention applies to design patents than to mechanical patents). An inventor under the patent laws is the “person or persons who conceived the patented invention.” C.R. Bard, Inc. v. M3 Sys., 157 F.3d 1340, 1352, 48 USPQ2d 1225, 1232 (Fed.Cir.1998).

An inventor may then “use the services, ideas, and aid of others in the process of perfecting his invention without losing his right to a patent.” Ethicon, Inc. v. United States Surgical Corp., 135 F.3d 1456, 1460, 45 USPQ2d 1545, 1548 (Fed.Cir.1998) (citing Shatterproof Glass Corp. v. Libbey-Owens Ford Co., 758 F.2d 613, 624, 225 USPQ 634, 641 (Fed.Cir.1985)). The facts are undisputed that the Hoop brothers were the first to conceive of the eagle-shaped fairing guards, and brought the concept to Mark and Lisa for assistance.

Thus in the absence of the inventive quality required for a patentable design on the part of Mark and Lisa, the Hoop brothers remain the true inventors. One may not qualify as a joint inventor, or as here, a new inventor, by “merely assisting the actual inventor after conception of the claimed invention.” Ethicon, 135 F.3d at 1460, 45 USPQ2d at 1548 (emphasis added). Minor differences between the prior art and the new claim will not suffice. In re Zemon, 40 C.C.P.A. 1051, 205 F.2d 317, 320, 98 USPQ 223, 224 (CCPA 1953).

The differences here must be substantial and not just superficial; the new design must contain an inventive concept. Id. The ultimate test for design-patent inventorship, like the test for anticipation and infringement, is whether the second asserted invention is “substantially similar” to the first. Gorham Mfg. Co. v. White, 81 U.S. (14 Wall.) 511, 528, 20 L.Ed. 731 (1871); Payless Shoesource, Inc. v. Reebok Int’l Ltd., 998 F.2d 985, 990, 27 USPQ2d 1516, 1520 (Fed.Cir.1993). Substantial similarity is a question of fact. L.A. Gear, Inc. v.

Thom McAn Shoe Co., 988 F.2d 1117, 1124, 25 USPQ2d 1913, 1918 (Fed.Cir.1993). The district court found that Mark and Lisa’s drawing lacked an “independent,” which we read as inventive, concept. The court summarized its improvements over the Hoop brothers’ sketch as increased detailed feathering and an overall less triangular shape. Noting the strong similarity between the drawings, the court reasoned that Mark and Lisa merely refined and perfected the Hoop brothers’ concept. Therefore, the two designs were not separate inventions.

Mark and Lisa did remove the suggestion of the eagle’s tail, see figure 2, but the two eagles have the same proportions, body size, orientation, three rows of feathers, head and beak shape, and eye placement. We agree that the trial court could permissibly conclude at the preliminary injunction stage that the second design was likely to be found to be merely a more refined version of the first. However, final resolution of this factual question must await a trial on the merits.

The court’s determination that the Hoop brothers are likely to be found to be the true inventors and that they are likely to succeed in sustaining the validity of their patent is sustained. Conclusion Accordingly, the order of the United States District Court for the Southern District of Ohio is affirmed. AFFIRMED.