In a significant ruling from the Morioka District Court, four trainers who received penalties for the detection of the banned substance boldenone in racehorses lost their appeal to have the penalties overturned. The judges rejected their claims, which alleged that the penalties—consisting of reprimands and suspension of awards—were unlawful, emphasizing the intrinsic responsibilities of trainers to uphold the integrity of the sport. This case stems from incidents that occurred between August 2018 and November 2019 during which boldenone, a muscle-enhancing drug, was found in a number of horses participating in Iwate horse racing.

The situation became complicated when the Iwate Police launched an investigation into possible violations of racing laws. However, the investigation determined it was likely that the horses ingested boldenone from straw used in the stables, leading to a conclusion that resulted in no criminal charges being filed. Despite this, the horse racing association imposed penalties on the trainers, which included a mix of reprimands and suspensions based on the findings of substance detection in the horses, particularly focusing on trainers of those horses that tested positive.

The court ruling highlighted the industry's reliance on a regulated system of oversight to sustain fair competition. The judges noted that even in the absence of negligence, the governing body has the authority to implement sanctions to maintain the efficacy of regulations governing horse racing. This case illustrates the tensions between compliance with regulatory standards and trainers' operational practices, underlining the broader implications for horse racing governance in Japan.