proceeding's administrator considers certain factors, such as the invention's conception date and the inventor's diligence in reducing the invention to practice. Until the 1960s, a junior party was frequently called an "interferant". Presumptions Presumptions are stated in 37 C.F.R. 41.207(a): (1) Order of invention. Parties are presumed to have invented interfering subject matter in the order of the dates of their accorded benefit for each count. If two parties are accorded the benefit of the same earliest date of constructive reduction to practice, then neither party is entitled to a presumption of priority with respect to the other such party. (2) Evidentiary standard. Priority may be proved by a preponderance of the evidence, except a party must prove priority by clear and convincing evidence if the date of its earliest constructive reduction to practice is after the issue date of an involved patent or the publication date under 35 U.S.C. 122(b) of an involved application or patent. Leahy-Smith America Invents Act On September 16, 2011, President Obama signed the Leahy-Smith America Invents Act into law. Part of the Act changed the U.S. patent system from a first-to-invent system to a first-to-file system. As such, interference proceedings for any patent application with an effective filing date on or after March 16, 2013, were eliminated from U.S. patent law. Derivation proceedings are replacing interference proceedings in the patent statutes, but the dispute surrounding a derivation proceeding is unrelated to that of an interference proceeding. References External links MPEP 2300.01 Introduction - 2300 Interference Proceedings (USPTO web site) United States patent law