Certain types of automation technology for navigation supporting is widely accepted in maritime industries. Furthermore, interest in autonomous ship operation has been growing from the view point of safety requirement. Tokyo University of Marine Science And Technology (TUMSAT) has developed a semi-autonomous ship which is operated remotely using long range Wi-Fi and can autonomously operate under conditions of wireless link disconnect. Throughout the development and operation planning process, discussions have been held between TUMSAT and government authorities relating to the establishment of laws and regulations to govern the operation of remotely controlled and autonomous marine vessels. In this paper, case studies and legal issues to be solved by collaboration of legal and engineering are presented.