The Athletics Integrity Unit (AIU) has appealed a decision that cleared U.S. sprinter Erriyon Knighton of doping charges related to a positive test for the banned substance trenbolone, which he attributed to eating contaminated meat. Knighton, who initially avoided a ban after the U.S. Anti-Doping Agency (USADA) found no fault or negligence, qualified for the Paris Olympics following the ruling. The AIU claims there was an error in establishing Knighton's lack of fault, prompting their appeal to the Court of Arbitration for Sport. USADA's CEO Travis Tygart criticized the appeal while defending the original decision, linking trenbolone's presence to common livestock practices. The controversy reflects ongoing tensions between U.S. and global anti-doping authorities, exacerbated by previous instances of contamination cases. Knighton's case highlights the complexities of anti-doping regulations and their implications for athletes' careers.