These regulations comprise Royal Decrees, Ministerial Regulations, Notifications of Directors General, as well as less formal policies and procedures followed by departments within the Thai government. The policies have not passed through the formal legal processes, but as a practical matter can be as significant as an Act of Parliament for one carrying out business in Thailand.

The central Thai law for business and much more is the Thai Civil and Commercial Code ("TCCC"). The TCCC specifies general principles and particular rules for the gamut of civil law issues influencing businesses and individuals. Some of the topics of special attention to businesses comprise company and partnership law, contracts, sales, obligations, unlawful acts (torts, such as liability for negligence or intentional harm), property, mortgage and other forms of loan security, leases and agency. For individuals, the TCCC accounts for marriage, divorce, wills and estate administration, and parental rights and duties.

The TCCC became Thai law in 1925. Notwithstanding regular and sometimes dramatic changes of government and constitutions in Thailand, the TCCC has resisted admirably, delivering a consistent legal framework and structure during otherwise turbulent times. The TCCC contains a few peculiarities that might interest a foreigner as, well, foreign, but for the most part the TCCC specifies legal principles common to most capitalist countries.

The French Civil Code was used as the beginning point for the TCCC, with Japanese, English, German and American legal scholars giving substantial input to the Thai law authorities at the time of drafting. While some contentious issues are surfacing when one considers the details, the basics of Thai law are consistent with the laws of business prevailing from Tokyo to Toledo.

According to the Thai judicial system, a trial court in Thailand is not influenced by prior court rulings when it settles an issue under the TCCC, or any other Thai law. Every case appearing before a Thai trial court is subject to the trial court judge's personal interpretation of the plain meaning of the applicable laws. Since the Thai laws, by necessity, are often not particular and sometimes not even plain, forecasting results on specific issues is sometimes an uncertain science. Still, the language of the TCCC is usually acceptable enough, and earlier court rulings - especially those of the Thai Supreme Court -act as reasonable guidelines for interpreting less certain provisions.

The TCCC is available across the country in English translation. The standard translation is the one done by late Professor Kamol Sandhikshetrin. While the TCCC is the central Thai law, there are undoubtedly many specific acts of significance when doing business in Thailand. One must have a clear idea about those specific acts before starting to do business in Thailand.