%O This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. %X Objectives: The police killing of George Floyd energized the Black Lives Matter (BLM) social movement across the United States in the summer of 2020. We test the impact on public perceptions of the fairness and legitimacy of the police and law. Methods: A four-state, three-wave, short-term longitudinal study (N = 1048; Arizona, Michigan, New York, and Texas) used a novel design focused on differences in change over time to test whether public perceptions changed after the killing of Floyd. Results: Fielding multiple outcome markers, as well as multiple pseudo-placebo comparison variables, we found that perceptions of police procedural justice, distributive justice, and bounded authority, as well as perceptions of the legitimacy of the police and law, declined following Floyd's murder. Levels of trust in science, identification with healthcare workers, and collective efficacy perceptions did not change. As discussed in the paper, the effects varied by participants’ political views. Conclusions: The police killing of George Floyd and subsequent protests seemed to have damaged attitudes towards police and the law. %L discovery10193468 %K procedural justice, police perceptions, police legitimacy, police brutality %J Journal of Research in Crime and Delinquency %D 2024 %A Adam Fine %A Thiago Rodrigues Oliveira %A Jonathan Jackson %A Ben Bradford %A Krisztian Posch %A Rick Trinkner %T Did the murder of George Floyd damage public perceptions of police and law in the United States?