Blood transfusion is a vital part of modern medicine, widely used in emergency care, surgery, and chronic illness management. But despite its lifesaving potential, transfusions can lead to serious harm if safety protocols are not strictly followed. Errors—ranging from mismatched blood types to administrative oversights—can cause severe complications, including hemolytic reactions and organ failure. This chapter explores how forensic investigations help uncover the causes behind such events by combining clinical records, autopsy results, and legal analyses. It also examines the role of regulatory bodies, ethical challenges, and emerging technologies like AI and blockchain in improving transfusion safety. Using real-world case studies and policy comparisons, the review offers a comprehensive look at the forensic, clinical, and legal dimensions of blood transfusion errors.