Law360, New York ( August 19, 2014, 8:14 AM EDT) -- For roughly 20 years, the loser in an interference proceeding who appealed to the U.S. District Court was confronted with Conservolite v. Widmayer, a 1994 Federal Circuit decision which generally restricted district courts from addressing new issues in a dispute over who has priority of patent.[1] District courts have obliged, often deferring to the Patent and Trademark Office's expertise, and allowed new evidence of priority only if it supported a theory raised before the Board of Patent Appeals and Interferences.[2] Recently, however, the Federal Circuit overruled Conservolite and held that parties may introduce any evidence in priority disputes in the district courts as long as the evidence is admissible under the Federal Rules of Evidence and Federal Rules of Civil Procedure.[3] In a major change in practice, any party may introduce new theories and evidence in the district court to show priority of invention....