The scholarship of Dean Hashimoto focuses on the interface of law, science and medicine, especially in the areas of health care policy and the role of scientific evidence in the courtroom.He has also studied the internment of citizens and aliens of Japanese heritage in World War II and written about the constitutional law cases decided in that era. 

Professor Hashimoto received his postgraduate medical training at the Brigham and Women's Hospital and the Harvard School of Public Health. He is a board-certified specialist in occupational and environmental medicine and serves as the chief of this specialty at the Massachusetts General Hospital and the Brigham and Women's Hospital.