Section 421 — Abuse of right — bad-faith use
Statutory text (Thai original)
การใช้สิทธิซึ่งมีแต่จะให้เกิดเสียหายแก่บุคคลอื่นนั้น ท่านว่าเป็นการอันมิชอบด้วยกฎหมาย
Verbatim from the Royal Gazette / Office of the Council of State
คำแปลภาษาอังกฤษ
The exercise of a right which can only have the purpose of causing injury to another person is unlawful.
This English translation is provided for reference only and has not yet been firm-verified — always rely on the Thai original.
Firm annotation
Section 421 is the close cousin of §5 (good faith) but in the tort chapter. It catches exercises of right where the dominant intent is to injure rather than to obtain any legitimate benefit. Classic Thai applications: a neighbour building a spite fence; a litigant filing a baseless action solely to drain the opponent; an employer terminating an employee on a technicality after the employee has reported wrongdoing. Note: §421 doesn't reach exercises of right that are merely insensitive — the plaintiff must show the dominant purpose was harm.
Why this matters in practice
Lawyers: Section 421 applies only where the right-holder has no genuine legitimate interest in the exercise and the sole purpose is to harm the other party. Courts apply this doctrine narrowly. A landowner who builds on or uses their own land in a way that incidentally harms a neighbour is not automatically liable — the plaintiff must show the action served no legitimate purpose of the right-holder. Laypersons: Even if someone technically has a legal right, using it solely to hurt you with no benefit to themselves can still be unlawful — but this is very difficult to prove.
Legislative history
Part of the original Civil and Commercial Code codification; no major subsequent amendment.
Supreme Court decisions interpreting this section
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Supreme Court Judgment No. 2573/2554 (2011)
A developer's interference with an access road that has become a statutory servitude for subdivision lot owners may constitute an abuse of rights under section 421 where the sole effect is to harm the lot owners.
A land developer had implicitly represented that a road shown in the subdivision plan would remain available. That road was encumbered as a public easement (servitude) under the applicable land-allocation regulations, and the developer was obliged to maintain it. The Court found that any interference with or denial of access to this servitude road could constitute both a violation of the servitude and, where done purely to inconvenience the lot owners, an abuse of rights under section 421.
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Supreme Court Judgment No. 8027/2546 (2003)
Section 421 does not apply where the plaintiff has not suffered special damage different from the general public; a private claimant cannot use section 421 to enforce rights against occupation of public land absent special prejudice.
The defendant occupied a strip of public land between the plaintiff's land and a public road by planting trees and building a bathroom. The plaintiff's land had not originally abutted the road, so the plaintiff had no prior access right across the public strip. The Court held this was not a case for section 421 (or section 1337): the plaintiff had not suffered special damage different from the general public, and the defendant's occupation of public land — while unlawful vis-à-vis the state — did not give the plaintiff a private cause of action for abuse of rights.
Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.