The bill introduces comprehensive regulations aimed at enhancing the safety and integrity of harness horse racing in Massachusetts under the Massachusetts Gaming Commission. Key provisions include the establishment of a Warning Light System for signaling accidents on the racetrack, which must be operated by judges and utilized by all licensees. Additionally, a Veterinarian's List will be created to monitor horses unfit for competition, alongside detailed Testing procedures for blood and urine samples, including protocols for handling split samples in the event of positive tests. The bill also outlines licensing requirements for drivers, trainers, and owners, emphasizing health standards for horses and the necessity for proper identification of all racing personnel. Further amendments focus on medication testing, claiming procedures, and postmortem examinations. The bill mandates a split sample chain of custody verification form and grants the Commission authority to retain samples for future analysis. It establishes that claims will be voided if a horse dies or is euthanized on the racetrack, and introduces new claiming procedures that require proper registration and consent from trainers. Additionally, it emphasizes the need for postmortem examinations for horses that die on association grounds, with a mortality review process to investigate such incidents. The bill aims to ensure compliance with regulations while addressing environmental contaminants and adopting the United States Trotting Association Rules, ensuring Massachusetts regulations take precedence in case of conflicts.