Section 420 — General principle of tort liability
Statutory text (Thai original)
ผู้ใดจงใจหรือประมาทเลินเล่อ ทำต่อบุคคลอื่นโดยผิดกฎหมายให้เขาเสียหายถึงแก่ชีวิตก็ดี แก่ร่างกายก็ดี อนามัยก็ดี เสรีภาพก็ดี ทรัพย์สินหรือสิทธิอย่างหนึ่งอย่างใดก็ดี ท่านว่าผู้นั้นทำละเมิด จำต้องใช้ค่าสินไหมทดแทนเพื่อการนั้น
Verbatim from the Royal Gazette / Office of the Council of State
English translation
A person who, wilfully or negligently, unlawfully injures the life, body, health, liberty, property or any right of another person, is said to commit a wrongful act and is bound to make compensation therefor.
This English translation is provided for reference only and has not yet been firm-verified — always rely on the Thai original.
Firm annotation
Section 420 sets out the four elements every tort claim must satisfy: (1) an act, (2) wilfully or negligently committed, (3) unlawful, (4) causing damage to a protected interest. Damage includes physical injury, economic loss, and infringement of intangible rights. Burden of proof rests on the plaintiff, but Thai courts have developed presumptions of negligence in specific contexts (traffic, medical malpractice, product liability).
Why this matters in practice
Lawyers: Prove all four elements: (1) a positive act or culpable omission; (2) fault — intent to cause harm or failure to meet the reasonable-person standard of care; (3) unlawfulness — violation of a protected right or legally prohibited conduct; (4) actual damage. The words 'any right' extend protection to statutory rights, constitutional rights, and recognised personal rights such as privacy. Laypersons: If someone harms you — physically, financially, or by violating a personal right — you can sue for compensation if you can show they acted intentionally or carelessly and broke the law.
Legislative history
Part of the original Civil and Commercial Code codification; no major subsequent amendment. Section 420 is modelled on the general tort clause found in civil law systems, particularly the German BGB §823.
Supreme Court decisions interpreting this section
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Supreme Court Judgment No. 1808/2561 (2018)
Concealing a material defect (expropriation) when selling property is a wrongful act that violates the buyer's protected rights as a consumer, rendering the seller liable under section 420.
A developer sold land and buildings to consumers without disclosing that part of the property had been expropriated. The Court held this constituted a wrongful act under section 420: concealing material information about the property being sold violated the consumers' rights as buyers and caused them actual damage, entitling them to compensation.
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Supreme Court Judgment No. 4893/2558 (2015) ★ Landmark
The constitutionally protected right to privacy is a 'right' under section 420; publishing intimate images without consent is a wrongful act regardless of press freedom.
Media defendants published intimate images of two private individuals taken without consent. The Court held that consensual sexual activity in a private setting is a constitutionally protected privacy right. Publishing such images unlawfully injured the subjects' constitutional right to privacy, a 'right' within the meaning of section 420, and the defendants were liable in tort regardless of their freedom of expression as media.
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Supreme Court Judgment No. 5374/2561 (2018)
Designating specific access routes within a development project for legitimate safety and management reasons is a lawful exercise of property rights, not a wrongful act under section 420.
The plaintiff developer built internal roads connecting to public roads on the east and west sides of a subdivision, intending all occupants to use only those designated access routes. When the defendant used an unauthorised route through the developer's property, the Court examined whether the developer's restriction of access constituted a wrongful act under section 420, finding that designating specific access routes for safety and management purposes was a legitimate exercise of property rights, not a tortious act.
Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.
Frequently asked questions
What are the four elements a claimant must prove in a tort claim under section 420?
The claimant must prove: (1) an act (or culpable omission) by the defendant; (2) fault — either intentional wrongdoing or negligence falling below the reasonable-person standard; (3) unlawfulness — the act violated a protected legal right or interest of the claimant; and (4) actual damage to the claimant's life, body, health, liberty, property, or other legal right. All four elements must be established; failure on any one defeats the claim.