Section 131: Duty to gather all evidence
Statutory text (Thai original)
ให้พนักงานสอบสวนรวบรวมหลักฐานทุกชนิด
เท่าที่สามารถจะทำได้ เพื่อประสงค์จะทราบข้อเท็จจริงและพฤติการณ์ต่าง ๆ อันเกี่ยวกับความผิดที่ถูกกล่าวหา เพื่อจะรู้ตัวผู้กระทำผิดและพิสูจน์ให้เห็นความผิดหรือความบริสุทธิ์ของผู้ต้องหา
English translation
The investigating officer shall collect all kinds of evidence, so far as he is able, in order to ascertain the facts and the various circumstances relating to the alleged offence, so as to identify the offender and to prove the guilt or the innocence of the accused.
This English translation is provided for reference only and has not yet been firm-verified. Always rely on the Thai original.
Firm annotation
This provision, in Chapter 1 (Ordinary Investigation), states the core purpose and duty of an investigation: to gather all available evidence, not only to prove guilt but equally to establish innocence. It is even-handed by design, requiring the officer to seek facts that exonerate as well as incriminate. The courts treat the extent of evidence-gathering as a matter of the investigator's discretion, so once he considers the evidence sufficient he need not pursue every additional line a party requests. It operates together with Section 130 (prompt, flexible investigation) and the seizure power in Section 85.
Why this matters in practice
Section 131 is a reminder that the investigation is meant to work both ways: the police duty is to gather evidence that could clear you as well as evidence against you. If there is exonerating evidence, it is worth ensuring the investigator is made aware of it early. That said, the courts allow the officer discretion over how far to investigate, so if requests for further inquiry are refused, the answer is usually to develop that evidence for trial rather than to attack the investigation itself. A consultation with a Thai lawyer can help you decide how to present exculpatory evidence.
Supreme Court decisions interpreting this section
-
Supreme Court Judgment No. 326/2566 (2023)
Under Section 131 the investigator gathers all kinds of evidence, whether he finds it himself or it is supplied by a party or outsider, to ascertain the facts, identify the offender and prove the offence and the true loss; evidence need not come from the injured person alone.
The Supreme Court held that under Section 131 the investigator gathers all evidence, including facts he traces himself, to establish the offence and the true loss. Where the investigator checked bank records and found transfers from the victim to the defendant totalling 3,023,352 baht, that was evidence gathered under his own authority and not required to come only from the injured person.
-
Supreme Court Judgment No. 8403/2561 (2018)
Section 131 gives the investigator discretion in gathering evidence; once he considers the evidence sufficient, he need not gather more or examine every witness the accused requests, and this does not make the investigation unlawful.
The Supreme Court held that under Section 131 the gathering of evidence is within the investigator's discretion. Once he considers the evidence sufficient, he may decline to gather more or to examine additional witnesses requested by the defendants, and this does not render the investigation unlawful.
-
Supreme Court Judgment No. 6877/2559 (2016)
Section 131 empowers the investigator to collect all kinds of evidence, so far as possible, to ascertain the facts and circumstances of the alleged offence, identify the offender, and prove the guilt or innocence of the accused.
In addressing whether the defendant official had committed an offence, the Supreme Court cited Section 131 as empowering the investigator to collect all available evidence to ascertain the facts and circumstances of the alleged offence, identify the offender, and prove guilt or innocence, read together with the seizure power in Section 85 paragraph three.
Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.
Cited in 15 Supreme Court decisions (1949 to 2023)
Selected citing decisions
- Decision 326/2566 (2023)
- Decision 5886/2558 (2015)
- Decision 6601/2554 (2011)
- Decision 2922/2528 (1985)
- Decision 1390/2522 (1979)
- Decision 1368/2500 (1957)
- Decision 8403/2561 (2018)
- Decision 1598/2494 (1951)
This list is selected automatically, weighted towards judgments that turn on this section rather than ones that merely recite it when passing sentence. It has not yet been reviewed by the firm.
Most often cited alongside
- Thai Penal Code s. 83 7
- Section 85 5
- Thai Penal Code s. 157 5
- Thai Penal Code s. 78 4
- Thai Penal Code s. 91 4
- Section 2 3
Sections that appear in the same judgments as this one most often. The figure is the number of decisions.
Counted across the firm's corpus of 83,652 Supreme Court decisions, 1921 to 2026. The count is complete; the stated year range trims rare outliers so it describes where the citations actually sit. These figures are computed by us and are not official court statistics. How we count these, and what we measured
Frequently asked questions
Does the investigator have to gather evidence that helps the accused?
Yes. Section 131 requires the investigator to gather all available evidence to prove the guilt or the innocence of the accused, so exonerating evidence is within his duty.
Can an investigator decline to gather more evidence?
Yes. The courts treat the extent of evidence-gathering as the investigator's discretion, so once he considers the evidence sufficient he need not pursue every further inquiry a party requests.
Can the investigator seize property as evidence?
Yes. To carry out the duty in Section 131, the investigator may seize or attach items, such as bank-account funds, as evidence relating to the alleged offence, in line with Section 85.
Related guides on ThaiLawOnline
Cite this section
-
Plain citation
Criminal Procedure Code, s. 131 (Thailand) -
Academic citation
Criminal Procedure Code (Thailand), s. 131. ThaiLawOnline, https://www.thailawonline.com/thai-criminal-procedure-code/section-131/ (accessed 11 August 2026). -
Thai citation
ป.วิ.อ. มาตรา 131 -
Permalink
https://www.thailawonline.com/thai-criminal-procedure-code/section-131/ -
Embed on your site
<blockquote cite="https://www.thailawonline.com/thai-criminal-procedure-code/section-131/"><p>The investigating officer shall collect all kinds of evidence, so far as he is able, in order to ascertain the facts and the various circumstances relating to the alleged offence, so as to identify the offender and to prove the guilt or the innocence of…</p><footer>Criminal Procedure Code, s. 131 (Thailand) — <a href="https://www.thailawonline.com/thai-criminal-procedure-code/section-131/">ThaiLawOnline</a></footer></blockquote>
The Thai text is authoritative. The English is an unofficial translation by ThaiLawOnline, free to reuse with attribution.