(April 5, 2017, 12:15 PM EDT) -- LOS ANGELES — Pop singer Katy Perry on April 3 prevailed in a dispute over her song “Dark Horse,” when a California federal judge agreed that Perry’s public performance of the work at concerts during her “Prismatic World Tour” cannot, at the summary judgment stage, form the basis of a copyright infringement claim (Marcus Gray, et al. v. Katy Perry, et al., No. 15-5642, C.D. Calif., 2017 U.S. Dist. LEXIS 50803)....