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70 American University Law Review 1269 (2021)


A fundamental criterion of patentability is that an invention must be new as compared to the prior art—the corpus of preexisting knowledge and technology already available to the public. If an invention is in the prior art, or rendered obvious by it, it cannot be patented.

The U.S. Patent Act has traditionally envisioned a categorical approach for deciding what counts as prior art. Under this approach, courts are supposed to decide whether a particular disclosure about the invention (a reference) falls within one of the categories listed in Section 102 of the Patent Act, such as “described in a printed publication,” “in public use,” or “on sale.” Yet the categorical approach lacks a coherent theory of publicness. It is difficult to find guiding principles to explain courts’ decisions about what is, or is not, public. For example, a woman wearing a corset invention at home under her clothing was deemed to be an invalidating “public use” that barred future patenting; yet an employee liberally sharing his invention with others at work was not.

We argue that, while courts refer to the statutory categories, they are in reality turning to concepts of publicness that strikingly resemble those of a different legal regime: trade secret law. Indeed, our review of the cases shows that trade secrecy status is dispositive for what counts as prior art in many of the leading cases. At a normative level, we argue that trade secrecy provides a surprisingly effective way to manage the boundary between legally public and legally secret information, and for deciding whether a reference is truly “available to the public” in the ways that matter for patent policy and, indeed, information policy more broadly. Not only does the trade secrecy standard protect peoples’ justifiable reliance on information that is already available to them, but it simultaneously makes inventors’ paths to patenting more efficient.