Section 138: Investigating the accused's background
Statutory text (Thai original)
พนักงานสอบสวนมีอำนาจสอบสวนเองหรือส่งประเด็นไปสอบสวนเพื่อทราบความเป็นมาแห่งชีวิตและความประพฤติอันเป็นอาจิณของผู้ต้องหา แต่ต้องแจ้งให้ผู้ต้องหาทราบข้อความทุกข้อที่ได้มา
English translation
The inquiry official has the power to conduct the investigation himself, or to send interrogatories for investigation, in order to ascertain the background of the life and the habitual conduct of the accused, but he must inform the accused of every item of information obtained.
This English translation is provided for reference only and has not yet been firm-verified. Always rely on the Thai original.
Firm annotation
Within Chapter 1 (Ordinary Inquiry), this section authorizes the inquiry official to look into the accused's background and habitual conduct, either directly or by sending interrogatories to be investigated elsewhere. The distinctive safeguard is transparency: every item of information obtained must be disclosed to the accused, so the inquiry cannot build a hidden character file. This background material can bear on the handling of the case and on sentencing considerations, and it operates alongside the recording and file-compilation duty in Section 139.
Why this matters in practice
If police look into your life history and habitual conduct, they must tell you every item they obtain, so you can respond to or correct anything that is inaccurate. Because this background can influence how your case and any sentence are handled, it is worth reviewing what has been gathered about you. If background material is being collected in your case, consider taking advice: you can book a consultation with a Thai lawyer.
Cited in 1 Supreme Court decisions (1989 to 1989)
Selected citing decisions
- Decision 4022/2532 (1989)
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.
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
Can police investigate my background during a criminal case?
Yes. Section 138 lets the inquiry official investigate the accused's life history and habitual conduct, either directly or by sending interrogatories.
Do I get to know what the officer found about my background?
Yes. Section 138 requires the inquiry official to inform the accused of every item of information obtained, so nothing may be kept from you.
Related guides on ThaiLawOnline
Cite this section
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Plain citation
Criminal Procedure Code, s. 138 (Thailand) -
Academic citation
Criminal Procedure Code (Thailand), s. 138. ThaiLawOnline, https://www.thailawonline.com/thai-criminal-procedure-code/section-138/ (accessed 11 August 2026). -
Thai citation
ป.วิ.อ. มาตรา 138 -
Permalink
https://www.thailawonline.com/thai-criminal-procedure-code/section-138/ -
Embed on your site
<blockquote cite="https://www.thailawonline.com/thai-criminal-procedure-code/section-138/"><p>The inquiry official has the power to conduct the investigation himself, or to send interrogatories for investigation, in order to ascertain the background of the life and the habitual conduct of the accused, but he must inform the accused of every item of information obtained.</p><footer>Criminal Procedure Code, s. 138 (Thailand) — <a href="https://www.thailawonline.com/thai-criminal-procedure-code/section-138/">ThaiLawOnline</a></footer></blockquote>
The Thai text is authoritative. The English is an unofficial translation by ThaiLawOnline, free to reuse with attribution.