Code de procédure pénale

Article 121: Investigator power and complaint requirement

Statutory text (Thai original)

พนักงานสอบสวนมีอำนาจสอบสวนคดีอาญาทั้งปวงแต่ถ้าเป็นคดีความผิดต่อส่วนตัว ห้ามมิให้ทำการสอบสวน เว้นแต่จะมีคำร้องทุกข์ตามระเบียบ

English translation

An investigating officer has the power to investigate all criminal cases. However, in the case of a compoundable offence (an offence against a private person), an investigation is prohibited unless there is a complaint lodged in accordance with the regulations.

This English translation is provided for reference only and has not yet been firm-verified. Always rely on the Thai original.

Firm annotation

This General Principles provision defines the scope of the investigator's authority and its single key limit. For public (state) offences the officer may investigate on his own initiative, but paragraph two makes a valid complaint an absolute precondition to investigating a compoundable offence. Because a lawful investigation is required before the prosecutor can file (Section 120), a defect here is fatal: with no valid complaint there is no power to investigate, and with no valid investigation the prosecutor has no power to sue. This is why the courts treat the question, often raised together with the meaning of injured person under Section 2(4), as one of public order.

Why this matters in practice

For compoundable offences such as embezzlement, fraud, or defamation, everything can turn on whether the right person lodged a valid complaint. If the complainant was not the true injured party, the investigation is void and the whole prosecution collapses, and the courts can raise this on their own even if the defendant never argued it. Victims should make sure the complaint is filed correctly and by the right person, and defendants should check whether it was. Getting this right often needs a lawyer, and our guide on how to choose a Thai lawyer can help.

Décisions de la Cour suprême interprétant cette section

  1. Arrêt de la Cour suprême n° 626/2565 (2022)

    A member of a savings group who has deposited money with it is herself an injured person under Section 2 (4) where that money is embezzled, and may complain without authority from the other members or from the committee. A complaint validly made under Section 121 paragraph two gives the inquiry official power to investigate and the prosecutor power to bring the case.

    Money that members had deposited with a savings group for production went missing while in the hands of the three defendants, whom the committee had chosen to look after it. The Supreme Court held the committee was an injured person under Section 2 (4) and could authorise someone to complain, and that the person it authorised was herself a depositing member and so an injured person in her own right, who could complain without authority from anyone. The complaint was valid, every member did not have to complain, the investigation was lawful and the prosecutor had power to bring the case. The Court of Appeal Region 5 had held otherwise and was reversed, and the case was sent back so that the remaining appeal points could be decided.

  2. Arrêt de la Cour suprême n° 404/2565 (2022)

    A person who is not the injured party by law under Section 2(4) has no right to lodge a complaint for a compoundable offence such as embezzlement; the investigator therefore has no power to investigate under Section 121 paragraph two, and the prosecutor has no power to file. This is a public-order point the court can raise on its own.

    Because the person who lodged the complaint was not the injured party by law, he had no right to complain about the alleged joint embezzlement, a compoundable offence. The investigator thus had no power to investigate under Section 121 paragraph two and the prosecutor no power to file. The Supreme Court raised the point on its own even though most defendants had not appealed it.

  3. Arrêt de la Cour suprême n° 3578/2564 (2021)

    Where the true injured party has not lodged a complaint for a compoundable offence such as joint mischief (damage to property), the investigator has no power to investigate under Section 121 paragraph two, the prosecutor has no power to file, and the victim cannot claim compensation in that count.

    The true victim of the property damage had not lodged a complaint, so the investigator had no power to investigate that charge under Section 121 paragraph two. The Supreme Court held the prosecution of that count was unlawful and the victim could not obtain compensation for the motorcycle repair in that count.

Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.

Cited in 71 Supreme Court decisions (1950 to 2025)

Décisions de citation sélectionnées

  • Decision 5119/2561 (2018)
  • Decision 4560/2558 (2015)
  • Decision 18162/2557 (2014)
  • Décision 15933/2557 (2014)
  • Decision 14785/2557 (2014)
  • Decision 11658/2557 (2014)
  • Décision 22714/2555 (2012)
  • Decision 9368/2555 (2012)

Cette liste est sélectionnée automatiquement, en privilégiant les jugements qui reposent sur cet article plutôt que sur ceux qui se contentent de le citer lors du prononcé de la peine. Elle n'a pas encore été examinée par le cabinet.

Le plus souvent cité aux côtés de

Sections qui apparaissent le plus souvent dans les mêmes jugements que celui-ci. Le chiffre correspond au nombre de décisions.

Calculé sur l'ensemble du corpus de 83 652 décisions de la Cour suprême du cabinet, de 1921 à 2026. Le décompte est exhaustif ; la plage d'années indiquée élimine les valeurs aberrantes rares afin de refléter la répartition réelle des citations. Ces chiffres sont calculés par nos soins et ne constituent pas des statistiques officielles de la Cour. Comment nous les comptons et ce que nous avons mesuré

Foire aux questions

La police peut-elle enquêter sur une infraction susceptible de transaction sans plainte ?

Non. En vertu de l'article 121, paragraphe deux, un enquêteur ne peut enquêter sur une infraction susceptible de transaction que si la personne lésée a déposé une plainte en bonne et due forme.

Que se passe-t-il si la plainte a été déposée par la mauvaise personne ?

Si le plaignant n'est pas la véritable partie lésée, l'enquête est illégale et le procureur n'a pas le pouvoir d'engager des poursuites ; l'affaire peut donc être classée sans suite.

Les infractions relevant de l'État nécessitent-elles également une plainte ?

Non. Pour les infractions publiques (d'État), l'enquêteur peut agir de sa propre initiative en vertu de l'article 121, paragraphe 1 ; l'exigence de plainte ne s'applique qu'aux infractions susceptibles de transaction.

Guides connexes sur ThaiLawOnline

Citer cette section

  • Citation simple Criminal Procedure Code, s. 121 (Thailand)
  • Citation académique Criminal Procedure Code (Thailand), s. 121. ThaiLawOnline, https://www.thailawonline.com/fr/thai-criminal-procedure-code/section-121/ (accessed 1 septembre 2026).
  • Citation thaïlandaise ป.วิ.อ. มาตรา 121
  • Lien permanent https://www.thailawonline.com/fr/thai-criminal-procedure-code/section-121/
  • Intégrer sur votre site <blockquote cite="https://www.thailawonline.com/fr/thai-criminal-procedure-code/section-121/"><p>Un officier enquêteur est habilité à enquêter sur toutes les affaires pénales. Cependant, en cas d&#039;infraction susceptible de transaction (une infraction contre une personne privée), aucune enquête n&#039;est possible sans plainte déposée conformément à la réglementation.</p><footer>Criminal Procedure Code, s. 121 (Thailand): <a href="https://www.thailawonline.com/fr/thai-criminal-procedure-code/section-121/">ThaiLawOnline</a></footer></blockquote>

The Thai text is authoritative. The English is an unofficial translation by ThaiLawOnline, free to reuse with attribution.

Ce document a une vocation pédagogique et ne constitue pas un avis juridique. Veuillez consulter un avocat thaïlandais qualifié avant de vous fier à toute disposition de ce document.

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