American boxer Claressa Shields , the undisputed world champion in three weight classes, has been suspended and is under investigation after testing positive for marijuana following her victory over heavyweight Danielle Perkins in Michigan. The Michigan Unarmed Combat Commission suspended the 29-year-old athlete from competing in the state after an “oral fluid sample” taken after the fight on February 2 showed the presence of marijuana, which is banned in competition by the World Anti-Doping Agency (WADA). “Ms. Shields’ conduct as a licensed professional boxer constitutes an immediate threat to the integrity of professional boxing, the public interest, and the welfare and safety of professional athletes,” the Michigan Commission said on Thursday. The World Boxing Organization (WBO), which does not have the authority to suspend boxers, has requested a “show notice” from Shields to provide an explanation.