He served as a court commissioner of the Pasadena Municipal Court from 1974 to 1980. Governor Jerry Brown appointed him as a judge on the Pasadena Municipal Court in 1980. In 1985, Governor George Deukmejian elevated Klausner to the Los Angeles Superior Court bench, where he served until 2002.[2] Klausner became supervising judge of the Criminal Departments in 1991 and assistant presiding judge in 1993; he was presiding judge from 1995 to 1996.[2] In this role, Klausner opposed a merger of the municipal and superior courts.[3]
In 2006, Klausner presided over United States v. Ancheta, the federal prosecution of Jeanson James Ancheta of Downey, California, the first botnet-related prosecution in U.S history. Following Ancheta's guilty plea, Klausner sentenced Ancheta to 57 months in prison for various botnet-related crimes.[6] In 2016, Klausner presided over a copyright case filed by the estate of Spirit guitarist Randy Wolfe against Led Zeppelin founders Robert Plant and Jimmy Page. The estate of Wolfe alleged that Wolfe was entitled to a writing credit for the song "Stairway to Heaven"; Klausner ruled in April 2016 that a jury could find "substantial similarity" between the elements of the two songs.[7] In another copyright case arising from the Star Trek fan film Prelude to Axanar, Klausner rejected various motions by both parties in January 2017, setting the stage for a civil trial on the matter to go forward.[8][9] The parties settled the suit.[10] In August 2017, Klausner dismissed a class-action lawsuit filed by boxing fans who contended that the 2015 Floyd Mayweather Jr. vs. Manny Pacquiao boxing match was deceptively marketed because Pacquiao failed to disclose a shoulder injury that affected his performance. Klausner ruled that fans of sporting events have no right to have the event meet their expectations for excitement.[11] In October 2017, Klausner ruled in favor of the plaintiff Coachella Music Festival in a lawsuit against the fledgling "Filmchella" film festival, finding that the names were likely to cause consumer confusion.[12]
On May 1, 2020, Klausner rejected a lawsuit by the United States women's national soccer team's for equal pay, ruling there was no genuine issue of material fact that they were discriminated against in pay.[13][14][15]
