The Leahy-Smith America Invents Act (AIA), Public Law 112-29, was adopted September 16, 2011 and introduced substantial changes to US patent law. It changed the US patent system from being a First-to-Invent system to a First-to-File system, thus bringing the US into line with the rest of the world and effectively eliminating Interferences for patents filed after its effective date, March 16, 2013. The act also introduced into US law pre-issue oppositions to patent grants, entitled preissuance submissions and expanded Inter Partes Reexamination renaming it Inter Partes Review. Finally the statute precluded the prior approach of filing patent infringement cases against large numbers of defendants which had been much used by Trolls, which inter alia led to a plethora of such cases being filed just before this restriction came into force.