.” The Ayutthaya and Sukhothai friendly as well, have the kidnapping of slaves fled to the northern city (Sukhothai) Victims appealed to the king carried out the slave returned. But, the king reply them to take back to the seller's agent only. The advantages of Thailand medieval law is strengthening of the rule and the political administration and Peace of Town and public morality, Law of the best must defend because, the law it must give protection to the public. People then peace Life Safety and property and the Kingdom. The fault of Ayutthaya law is the trial unfair it is because the social conditions in those days, that there is no development and not formulate precise rules. So the law Ayutthaya Revolution has to resolve until the Rattanakosin period.