The development of the Thai legal system in southern middle reign 4 need to improve the legal system to the modern. To modify this is not only in Thailand. But many countries in Asia are fall in the same condition.Cannot be used in contact with foreigners who come into contact with the governor or trading in time effectively.Commercial law and maritime law in respect of techniques, such as tax collection law is complex, etc., which when brought these issues to compare with the modern law of the ตกจ found that.Thailand must accept the principle of modern western come to solve problems. During his reign he has adopted many 500 of joint law law adopted in time.