Trade Secrets

Bonito Boats v. Thunder Craft: When a State Cannot Re-Create the Patent Monopoly

A unanimous Supreme Court struck down Florida's anti-plug-molding statute, holding that a state may not grant patent-like protection to an unpatented design already disclosed to the public — and explaining why trade-secret law survives the same test.

July 21, 2025
A fiberglass boat hull in a manufacturing mold
Once the hull was sold without a patent, federal law made its shape free for the taking. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

Bonito Boats, Inc. v. Thunder Craft Boats, Inc., 489 U.S. 141 (1989), No. 87-1346, is the modern Supreme Court statement of how far a state may go in protecting designs their owners never patented. Argued December 5, 1988, and decided February 21, 1989, in a unanimous opinion by Justice O’Connor, the case invalidated a Florida statute that forbade copying boat hulls by a particular molding process. For anyone weighing how to protect a product’s appearance — patent, trade dress, secrecy, or hope — Bonito Boats draws the constitutional boundary: a state cannot offer a substitute patent for what its owner placed, unprotected, into the stream of commerce.

The dispute grew out of an ordinary manufacturing reality. Bonito Boats developed a fiberglass recreational boat hull, marketed as the Bonito 5VBR, and sold it without filing any patent application on the hull’s design or the process used to make it. Six years after the boat reached the market, the Florida Legislature enacted a “plug molding” statute, codified at Fla. Stat. § 559.94, that made it unlawful to use the direct molding process to duplicate an unpatented vessel hull for sale, and forbade the knowing sale of hulls so duplicated. Bonito sued Thunder Craft under the statute. The Florida courts, and ultimately the Florida Supreme Court, held the statute preempted. The U.S. Supreme Court agreed.

At a glance

  • Case: Bonito Boats, Inc. v. Thunder Craft Boats, Inc., 489 U.S. 141 (1989)
  • Docket: No. 87-1346
  • Argued / decided: December 5, 1988 / February 21, 1989
  • Court: Supreme Court of the United States (O’Connor, J., for a unanimous Court)
  • Below: Supreme Court of Florida (No. 68,829), affirming dismissal of the claim
  • Statute at issue: Fla. Stat. § 559.94 (anti-direct/“plug” molding of unpatented boat hulls)
  • Core holding: By according patent-like protection to the otherwise unprotected design and utilitarian aspects of a product in general circulation, the statute intruded on a field reserved to Congress and was preempted by the Supremacy Clause.
  • Why it matters: It defines the constitutional ceiling on state design protection and explains why trade-secret law, by contrast, survives preemption.

The patent bargain as a ceiling on state law

Justice O’Connor’s opinion is, in effect, a tour of the federal patent bargain and the public’s countervailing right to copy. The federal scheme offers a limited monopoly only in exchange for a meaningful contribution to the art and full public disclosure; everything that fails to clear the patent system’s demanding thresholds of novelty and nonobviousness is meant to remain free for all to use. That free-use principle is not a gap in the law to be filled by the states. It is, the Court emphasized, an affirmative federal policy — the other half of the patent bargain.

The Florida statute collided with that policy head-on. It conferred a right to exclude others from copying a design that its owner had publicly disclosed by selling it, had never submitted to patent examination, and could not necessarily have patented at all. In doing so it offered, as the Court put it, patent-like protection for ideas the federal scheme had left unprotected. A state may not, the Court held, “offer a substantial financial inducement for invention through reverse engineering” — that is, it may not give an unpatented, publicly available design the very exclusivity that the patent laws reserve for inventions that have run the federal gauntlet.

Crucially, the Court reaffirmed Sears, Roebuck & Co. v. Stiffel Co., 376 U.S. 225 (1964), and Compco Corp. v. Day-Brite Lighting, Inc., 376 U.S. 234 (1964), the foundational decisions establishing the public’s right to copy unpatented articles. Bonito Boats refused invitations to read those cases narrowly and instead confirmed their core: states cannot prohibit the copying of unpatented, unprotected designs in general circulation.

Reverse engineering and the right to copy

The mechanism the statute outlawed — direct or “plug” molding, in which a competitor uses an existing finished hull to make a mold and then casts copies — is a form of reverse engineering. The Court treated the right to reverse engineer a publicly sold product as central to the federal balance. Competitors who study, measure, and reproduce an unpatented article in general circulation are doing precisely what the patent system contemplates as the price of non-disclosure-via-patent: the inventor who declines the patent bargain keeps no monopoly against the public’s study of what was sold.

Florida had tried to carve out one efficient method of copying while leaving others nominally available. The Court was unpersuaded. Forbidding the cheapest and most effective means of duplicating an unpatented design still erects a barrier to entry that mimics the patent right, and it does so without any of the patent system’s disciplining requirements — examination, a defined and limited term, or disclosure that enriches the art. The defect was not the particular technique singled out but the kind of protection the statute conferred.

Why trade-secret law survives the same test

The most strategically important passage for trade-secret practitioners is the Court’s careful reconciliation of Bonito Boats with Kewanee Oil Co. v. Bicron Corp., 416 U.S. 470 (1974), which had upheld state trade-secret law against patent preemption. The reconciliation turns on a single variable: public disclosure.

Trade-secret law protects information because it is kept secret. It does not remove anything from the public domain — the public never had it — and it explicitly tolerates the two things the patent bargain protects: independent invention and reverse engineering of lawfully obtained products. A trade secret evaporates the moment it is fairly reverse engineered or independently discovered. The Florida statute did the opposite. It reached designs already fully disclosed to the public through sale and forbade the very reverse engineering that trade-secret law permits. That is why secrecy-based protection coexists with federal patent policy while a state anti-copying statute for publicly sold goods cannot. The line is disclosure: protect what you keep secret, and you stay within the states’ domain; try to protect what you have publicly sold without a patent, and you trespass on Congress’s.

Open questions

Bonito Boats leaves the boundary between permissible and preempted state protection contestable at its margins. It does not precisely locate where consumer-deception-based unfair competition or trade-dress protection — which polices source confusion rather than copying as such — gives way to impermissible design monopoly; later trade-dress decisions, especially TrafFix Devices, Inc. v. Marketing Displays, Inc., 532 U.S. 23 (2001), continued to police that frontier through the functionality doctrine. The opinion also did not address how its logic applies to sui generis federal regimes that protect designs outside the utility-patent system, a question Congress soon answered for boat hulls specifically. And it leaves room for debate over which copying techniques, if any, a state may regulate on grounds unrelated to mimicking the patent right (for example, misappropriation of a competitor’s actual labor in certain narrow circumstances).

Implications

  • Disclosure forfeits the design unless a patent covers it. Selling an unpatented product puts its appearance and utilitarian features into the public’s right-to-copy, and no state statute can claw that back.
  • Secrecy, not state anti-copying law, is the durable non-patent shield. Trade-secret protection survives because it depends on secrecy and tolerates reverse engineering; it is the strategy Bonito Boats leaves intact.
  • Reverse engineering of public products is a protected federal interest. Banning even the most efficient method of copying an unpatented article reads like a patent and will be preempted.
  • If you want exclusivity in a design, use a federal regime. Design patents, and after this case the Vessel Hull Design Protection Act of 1998 (17 U.S.C. ch. 13), are the lawful routes — Congress, not the states, supplies design exclusivity.
  • Trade dress is policed by confusion and functionality, not by copying as such. Source-identifying, non-functional features may be protectable; the design itself is not.

Frequently asked questions

What exactly did the Florida statute do, and why was that fatal? It barred using the direct molding process to copy an unpatented boat hull for sale. The Court held this gave patent-like exclusivity to a publicly disclosed, unpatented design, intruding on the field Congress reserved through the patent laws, and so was preempted by the Supremacy Clause.

If states cannot protect such designs, how does trade-secret law survive? Because trade-secret law protects only information kept secret and permits reverse engineering and independent discovery. It withdraws nothing from the public domain. The Florida statute reached designs already publicly sold and forbade the reverse engineering that trade-secret law allows — the opposite posture.

Did boat-hull designers end up with any protection after this case? Yes. Congress responded in 1998 with the Vessel Hull Design Protection Act (17 U.S.C. §§ 1301–1332), a federal sui generis scheme granting roughly ten years of registration-based protection for original hull designs — federal protection supplying what the states could not.

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