Lt Cdr Barker is a barrister and serving Officer in the Royal Navy specializing in public international, criminal and administrative law. He has served on 6 ships on a range of global operations, most recently deploying for 9 months to the Middle East. He has served as legal advisor to the UK Maritime Battle Staff and Higher Command and Staff Course. Other assignments have included the staff of Commodore Naval Legal Services advising Commanding Officers and fatal accident inquiries and on the staff of the Chief of Joint Operations. With rights of audience in all courts of England and Wales, Lt Cdr Barker has prosecuted and defended in the Court Martial and Court Martial Appeal Court.