Reversal was required where irrelevant and highly prejudicial evidence of gang membership was improperly admitted. During appellant’s trial for attempted murder with gang enhancements charged pursuant to Penal Code section 186.22, the prosecutor introduced evidence of gang affiliation. Appellant had sought to exclude the evidence, arguing that it was irrelevant to the charges and inadmissible under Evidence Code section 352. The trial court concluded that the gang evidence was relevant and not overly prejudicial on the issue of intent and motive for the underlying charges, (i.e. that appellant committed the crime to gain respect of the gang.) On appeal from his conviction, appellant contended that the trial court should not have admitted the gang evidence (or should have granted his new trial motion in its entirety) because the gang evidence was irrelevant and highly prejudicial. He contended that the erroneous admission of the evidence was prejudicial error under state law, and also rendered the trial fundamentally unfair, in violation of federal due process. The appellate court agreed and reversed. The trial court should have granted the new trial motion in its entirety. Certain extremely prejudicial gang evidence (threats against police, reference to the Mexican Mafia, descriptions of other crimes committed by gang members) was not relevant to the underlying charges, and the prosecutor failed to present sufficient evidence that the crimes were gang motivated. The paramount function of the evidence was to show appellant’s criminal disposition. The case was one of those rare and unusual occasions where the admission of evidence violated federal due process and rendered the trial fundamentally unfair. Given the prejudicial nature of the evidence, it cannot be said that the error did not contribute to the verdict, and therefore the trial court erred when it failed to grant the new trial motion on all the charges.