Innovations such as artificial intelligence (AI) and decentralized clinical trials (DCTs) offer opportunities to enhance trial quality and efficiency. However, these innovations raise ethical questions about key responsibilities in research, such as participant safety and data quality. Using an example of an AI system determining personalized medication dosages in a DCT, we highlight how these technologies diffuse responsibilities among multiple actors and technologies. Diffusion diminishes the ability of actors to fulfill responsibilities. To address this, leading actors, such as sponsors, should prioritize overseeing responsibility attribution and implementation. This involves mapping responsibilities, identifying risks and challenges for fulfilling these responsibilities, and organizing adequate communication channels.