When activities are delegated to a service provider, the investigator still bears the overall responsibility for the conduct of the trial at the site. This means ensuring that protocol procedures are followed, participant rights and safety are protected, informed consent is properly obtained and documented, data are accurately collected and reported, and regulatory obligations are met. The investigator must supervise the service provider, verify the quality of work, and be able to account for all trial activities to sponsors, regulators, and ethics bodies. Delegation is permitted, but accountability does not transfer away from the investigator. The sponsor does not take on all responsibility simply by delegating tasks, and the service provider cannot be solely responsible for the trial’s conduct. The IRB oversees ethical review and ongoing safety monitoring, but it does not manage day-to-day trial execution.