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.