Specialisms include, but are not limited to:

Accident, assault, injury, trauma, wounding, personal injury, medical negligence, road traffic act, drink and drug driving, drug and alcohol misuse, clinical forensic medicine, fitness to detain, fitness to be interviewed and sexual assault.

Death in custody, rape, torture and historic torture. Care in custody, police complaints, neglect, adult and child abuse, non-accidental injury, restraint injury, thrombophlebitis, assessment of post-mortem stomach contents, strangulation, and self-inflicted injury.

Professor Payne-James is also an accredited mediator, hold the EC certificate of specialist training (Gastroenterology) and President of the European Council of Legal & Forensic Medicine.

Professor Payne-James was the past President of the Faculty of Forensic and Legal Medicine and acted as an Expert Witness in various complex medico legal cases. He is past Lead Medical Examiner at NNUH and Medical Director of Forensic Healthcare Services Ltd.

He has provided evidence to the Baha Mousa, Al-Sweady and Sheku Bayoh Public Inquiries in the UK.

He has given expert opinion for a wide variety of bodies overseas and have given live evidence or produced written reports for a variety of jurisdictions and courts including Kenya, Ireland, Scotland, Spain, Malta Channel Islands, Hong Kong, Mexico, Eire, New Zealand, Gibraltar, India, federal court in the USA and the Turks and Caicos Islands.

Although working outside a formal academic setting Professor Payne-James has consistently developed, lead, undertaken and published a wide range of research in a number of areas including forensic medicine and science, clinical nutrition and gastroenterology since the mid 1980s.

His current research interests are predominantly related to healthcare in custody, death investigation, restraint techniques, including Taser® and irritant spray, excited delirium, evidential sampling, restraint deaths, death and harm in custody, spithoods, hospital referrals, complaints against healthcare professionals, Medical Examiner roles, stalking in forensic medicine and the quality of recording and imaging of injuries.

He has particular interests in the disproportionate application of use of force techniques on specific groups and vulnerable individuals. He was Chair of the UK Scientific Advisory Committee on the Medical Implications of Less-Lethal Weapons from 2021-2025.

He has published approximately 350 papers, abstracts, articles, chapters and books, and is the leading author of forensic textbooks published worldwide.