Law of Thailand
The laws of Thailand are based on the civil law, but have been influenced by common law (see also world legal systems). Sources of law

The Rattanakosin Kingdom and the four traditionally counted preceding kingdoms, collectively called Siam, had a largely uncodified constitution until 1932. In the King of Siam's preamble to the penal code promulgated on 1 April 1908, and came into effect on 21 September, the king said: "In the ancient times the monarchs of the Siamese nation governed their people with laws which were originally derived from the Dhamasustra of Manu, which was then the prevailing law among the inhabitants of India and the neighbouring countries." The principal law sources in Thailand are:
 Constitution of Thailand - prevails over other laws. Acts and statutes - Many of which created and amended the 4 basic codes: Civil and Commercial Code (CCC), Penal Code (PC), Civil Procedure Code, and the Criminal Procedure Code. Newer codes include the Land Code and the Revenue Code. Years on Thai statutes are dated with the Buddhist Era (BE) year based on the Thai solar calendar. Emergency decree or royal proclamation - these are issued by the king, upon the advice of the cabinet, where an urgent law is needed for national security, public safety, national economic stability, or to avert a public calamity. An example is the Emergency Decree on Public Administration in Emergency Situation BE 2548 (2005). Treaties
 Subordinate legislation - Regulations (ministerial), orders, notifications, royal decrees, and rules. Supreme Court opinions and other judicial decisions - Judicial precedent in Thailand is not binding. Courts are not bound to follow their own decisions. Lower courts are not bound to follow precedents set by higher courts. However, Thai law has been influenced by common law precedent. Courts are therefore significantly influenced by earlier decisions or decisions of higher courts. The Supreme Court of Justice publishes its decisions, known as "Supreme Court Opinions". These are frequently used as secondary authorities and are numbered according to the year issued. Other judicial decisions or rulings are published by the Administrative Court and the Constitutional Court. Public law

Constitutional law
The Constitution of Thailand is the supreme law of Thailand which prevails over other laws passed by parliament. The 2017 constitution of Thailand is the most recent constitution. The Constitutional Court of Thailand has jurisdiction to make rulings over the constitutionality of parliamentary acts, royal decrees, draft legislation, appointment and removal of public officials and issues regarding political parties and civil liberties. Criminal law
Criminal offences (that can lead to arrest and imprisonment) are enumerated in the Thai Penal Code (or Criminal Code) as well as numerous other statutes. Criminal procedures are outlined in the Criminal Procedure Code. Drug offences are dealt with by several statutes. The  BE 2522 (1979) defines narcotics, classifies them into categories, details offences and outlines punishments. Penalties for producing, importing or exporting narcotics are outlined in sections 65–102 (Chapter 12) and include fines, life imprisonment or death. Other narcotics laws include the Psychotropic Substances Act BE 2518 (1975) and the Narcotics Control Act BE 2519 (1976). The offence of lèse majesté is found in the Criminal Code. Article 112 states that "Whoever defames, insults or threatens the King, Queen, the Heir-apparent or the Regent, shall be punished (with) imprisonment of three to fifteen years" (see also lèse majesté in Thailand). Administrative law
Administrative law matters such as judicial review are handled by the Administrative Court, which was established under The Act on Establishment of Administrative Courts and Administrative Court Procedure BE 2542 (1999). The jurisdiction of the court includes unlawful act by an administrative agency or State official (e.g., ultra vires, inconsistent with law, bad faith etc. ), neglecting or unreasonable delay in official duties, wrongful act or other liability of an administrative agency, administrative contracts, mandating a person to do something or an injunction. Immigration law
Visa and immigration law is outlined in the Immigration Act BE 2522 (1979) and its amendments. The Immigration Bureau of the Royal Thai Police administers the law, while the Immigration Commission shall have power and duty to make decision such as giving or revoking permission to stay. Private law
The most important reference of private law (or civil law) is the Civil and Commercial Code of Thailand (see also other civil codes). It is composed of several books. Books I and II were first promulgated on 11 November 1925 (BE 2466). The Civil code is updated as required by amendment acts (for example Act Amending Civil and Commercial Code (No 14) BE 2548 (
The Law of Obligations in general is found in Civil and Commercial Code sections 194 to 353 (Book II, Title I). Quasi-contracts include undue enrichment,  sections 406 to 419 (Book II, Title IV), and management of affairs without mandate, sections 395 to 405 (Book II, Title III). The main source of contract law is the Civil and Commercial Code sections 354 to 394 (Book II, Title II). Specific contracts (Sale, Hire, Mortgage, Insurance, Bills etc.) are found in the Civil and Commercial Code sections 453 to 1011 (Book III, Titles I to XXI). Tort or delict law
Tort law or delict law falls within the law of obligations. It is found in the Civil and Commercial Code sections 420 to 452 (Book II, Title V). The Code deals with wrongful acts: liability, compensation and exemptions to liability (justifiable acts). Corporate law
Basic corporate law is found in the Civil and Commercial Code sections 1012 to 1273 (Book II, Title XXII). Foreign ownership of certain Thai industries and foreign companies in general are regulated by the Foreign Business Act BE 2542 (1999). Personal property law
The main source of property law is the Civil and Commercial Code sections 1298 to 1434 (Book IV). Land law
Land law is dealt with by the Land Code. This was established by Act Promulgating the Land Code, B.E. 2497 (1954). Land in Thailand is covered by a system consisting of several title deeds offering different rights of use, possession, ownership or alienation. Most titles are issued by the Land Department and fall within seven main categories. Another five categories are issued by other government departments for specific purposes. The Chanote (or Nor Sor 4 Jor) category, found in more developed parts of Thailand, offers private ownership (similar to freehold land). Other land is considered to belong to the government or the King of Thailand. Intellectual property

Intellectual property law, that is patents, trademarks and copyright, are protected by the Patent Act BE 2522 (1979), Trademark Act BE 2534 (1991) and the Copyright Act BE 2537 (1994) and their amendments respectively. Trade secrets are protected by the Trade Secrets Act BE 2545 (2002). The Department of Intellectual Property (DIP) manages intellectual property matters such as registration and enforcement. A registration system exists for trademarks and patents. Copyright is automatically protected for 50 years and does not need registration, however it can be filed with the DIP. Disputes are first heard in the Intellectual Property and International Trade Court. 