Probative or Prejudicial: Can Gang Evidence Trump Reasonable Doubt? Mitchell Eisen Brenna Dotson Gregory Dohi AbsTRACT Tis study was designed to examine the potential biasing efect of gang evidence on jury verdicts. Two hundred four participants viewed one of two versions of a simulated trial that included opening statements and closing arguments by the prosecution and defense, and direct and cross-examination of the eyewitness and investigating ofcer. Half of the participants saw a version of the trial that included no mention of gang involvement, while the other half saw a version in which the prosecutor argued at opening and closing that the crime was committed for the beneft of a criminal street gang. In the gang version, participants also heard testimony from a gang expert who described the primary criminal activities of the gang. Jurors were read standard California jury instructions and deliberated in small groups. Te prosecution’s case was very weak by design. Results revealed that when mock jurors were polled before deliberations, only 13 percent who saw the trial without gang evidence voted guilty compared to 36 percent in the gang condition. After deliberation, none of the jurors found the defendant guilty in the no-gang condition. However, when gang evidence was introduced, 10 percent of the jurors continued to vote guilty. When faced with potent gang testimony in the absence of persuasive evidence, some jurors appeared to disregard reasonable doubt and vote to convict the defendant who was depicted as a dangerous gangster. Tis behavior appears to be driven by a form of jury nullifcation in the reverse direction, in which the defendant is judged to be deserving of punishment despite a lack of evidence related to the charge at hand. Implications of these data in the courtroom are discussed. AuThoRs Mitchell Eisen Ph.D., Brenna Dodson M.S., California State University, Los Angeles. Gregory Dohi, J.D., Los Angeles County Superior Court Judge, Adjunct Associate Professor, Southwestern Law School. Acknowledgements: We would like to thank Millan Djanbazian, Madhavi Guiot, Amani Hamed, Oriana McGee, Marilyn Orozco, Diamond Orso, Maisam Othman, Christine Schemezle, Giovanna Tavera, and Carli Yoneda for their work in collecting and entering the data, and Judge Darrell Mavis of the Los Angeles Superior Court for allowing us to combine our mock trial with his trial advocacy class at Southwestern Law School. All correspondence related to this article should be directed to Mitchell Eisen Ph.D., Department of Psychology, California State University, Los Angeles, Los Angeles, CA 90032. Email: meisen@calstatela.edu. uCLA LAW REVIEW DIsCouRsE 62 UCLA L. Rev. DisC. 2 (2014)