The law is a control conduct situation in society, developed from the morals, customs, customs, religion, and the statutes, regulations, respectively. The objective is to maintain the public order and moral of the members in the society. Meet the needs of various sectors appropriately.
The ancient origins of Thai Law was based on the Hindu code of Manu. During the Sukhothai period (1238–1350 AD), there was no system of Justice since the King was "the Fountain of Justice" who alone settled disputes between the people.
The Thai legal system has historically revolved around the monarchy. The traditionally accepted Thai view of the monarchy during the Sukhothai period, when the population and the area of the kingdom were both relatively small, was of a familial, patriarchal king. This changed as the Thai capital moved south and Thai kings controlled more land and people. The Thai view of kingship which was adopted during the Ayudhya period retains astonishing power even today, as Thailand prepares to join the ranks of developed countries.
During the Ayutthaya Period (1351–1767 AD), the first semblance of a legal system emerged. The law code was the Royal Stone Inscription which was formulated from a set of rules derived from the Kings' decisions in the Court of Law. Although the law code allowed for people to be represented in court for civil and criminal matters, the lawyer's work was limited. He could not be involved in the examination of witnesses before the court and was mainly concerned with writing plaints and filing them before the court.
In Ayudhya Thai thought on kingship was influenced by the Mon, an indigenous people, and the Khmer, against whom the Thai frequently waged war. The legal systems of both the Mon and the Khmer had been developed from the Hindu dharma-sastras. The Thai thammasat is a Buddhist interpretation of the dharma-sastras as the Thais received them from the Mon and the Khmer. The thammasat was central to the Thai legal system until the reforms of King Chulalongkorn in the late 19th and early 20th centuries. Its view of the king as a righteous god who embodies the law continues to influence the common Thai's concept of kingship
The thammasat was considered sacred or natural law. It was deemed to be the supreme expression of truth and equity as revealed by a supernatural source; its provisions were sacred and eternal. Thai kings, although regarded as divine, could not make a law which was not in harmony with the thammasat . Laws made by kings ( rachasat ) tended to be considered temporary reflections of the power of the king, while the natural law of the thammasat was regarded as eternal. The thammasat "changed the basis of political leadership from an intimate and informal paternalism to an idealized monarch who was expected to rule his subjects with justice and moderation."