I. IntroductionIn 2011, Congress enacted the America Invents Act (AIA), the most substantial overhaul of the patent system in the past sixty years. The most significant change in the AIA was the move from a to invent regime to a inventor to regime. Before 2011, U.S. patent law chose among competing claimants to a patent by favoring the first to invent. Under the AIA, we (largely) follow the rest of the world in awarding the patent to the first inventor to file a patent application.The goal of the move to (mostly) first to file, besides harmonization, is to encourage inventors to move with alacrity to share their invention with the world. Under the new law, an inventor can't rest on merely having invented; they have to race to the Patent and Trademark Office (PTO) in hopes of beating competitors. Under the AIA, unlike many other countries, inventors can also satisfy the obligation to share the invention with the world by making a such as a publication or a sale; doing so gives the inventor a year to get her invention on file. But whether it is by filing a (later-published) patent application or by publishing the invention, one of the touted advantages of the AIA is that it will encourage inventors to promptly disclose their ideas to the public.1There is an ambiguity in the AIA, however, that threatens that disclosure objective. Some commentators have argued that Congress intended to fundamentally change the rules of prior art in a way that would encourage secrecy rather than disclosure.2 Under this interpretation of the new law, an inventor can its process in secret for commercial purposes, potentially forever, and still file a patent on that invention at some point in the future. Far from encouraging disclosure, on this interpretation the effect of the AIA is to encourage secrecy and delay in patenting. Curiously, the argument is that Congress signaled its intent to make this fairly radical change by reenacting language that had been in the Patent Act for the last 140 years: the words use.Because two of these commentators, Bob Armitage and Joe Matal, were involved in the drafting of the AIA,3 this argument has carried substantial weight, and the PTO in 2013 adopted regulations that read the term use in the AIA as meaning something completely different than it had for the century before 2011.4In this Essay, I make two points. First, as a matter of statutory interpretation it is unlikely that Congress intended to make such a change, only because they readopted existing statutory language but because other parts of the statute make no sense under such an interpretation. Second, reading the AIA as making such a change would be unwise as a policy matter, only because it would encourage secrecy but because it would undermine confidence that other terms reenacted in the AIA have the same meaning they have accrued in decades of common law.In Part II, I explain the rules that existed before 2011. In Part III, I explain the changes made by the AIA and how they have been interpreted to date. In Part IV, I consider whether those changes result in use meaning something different under the AIA than it did before 2011.II. Prior Art and Public Use Before the AIAAn inventor can obtain a patent only if the invention is novel-that is, that no one has done the same thing before.5 Rather than adopting an absolute novelty rule, however, patent law has traditionally required that most categories of prior art be accessible to the public.6 Thus, while 35 U.S.C. § 102(a) bars a patent if the invention was or used by others before the applicant invented it,7 courts have interpreted that term to mean publicly known or used.8 At the same time, the accessibility requirement does require that the have a realistic chance of accessing the information; public seems to mean merely not secret. …