Physics Today Recent developments in US patent law Patrick M. Boucher January 2012, page 27
http://dx.doi.org/10.1063/PT.3.1397 "...Since its early history, the US has operated under a “first-to-invent” patent system in which the question of who wins the race to the patent office is less important than who invented something first (see the article by James Richardson and Craig Wood in PHYSICS TODAY, April 1997, page 32). That system will change on 16 March 2013. The change implemented by the Leahy–Smith America Invents Act that has attracted the most attention is often informally described as a move from the first-to-invent system to a “first-to-file” system. Characterized that way, the concept is deceptively simple: The first person to file a patent application for an invention is the one entitled to the patent. The reality, though, is considerably more complex. First, the act does not implement a pure first-to-file system, but rather implements a variation referred to as a “first-inventor-to-file” system. The distinction is important, particularly for scientists, because a major difference from a pure first-to-file system is that it permits, and even encourages, publication of the invention before it is filed with the patent office—provided the applicant adheres to certain critical provisos..." Harry
