Section 59 — Intention, negligence and criminal act
English translation
A person shall be criminally liable only when the act is committed intentionally, except where the act is committed through negligence in a case for which the law provides for liability when committed through negligence, or except in a case where the law expressly provides for liability even for an act committed without intention.
To commit an act intentionally means to commit it with consciousness of the act and, at the same time, the doer intends the result of, or can foresee the result of, such act.
If the doer did not know the facts constituting the elements of the offence, it cannot be held that the doer intended the result, or could foresee the result, of the act.
To commit an act through negligence means to commit an offence not intentionally but without the care which a person in such a situation must exercise according to the circumstances and condition, and which the doer could have exercised but failed to exercise sufficiently.
An act shall be deemed to include causing a result by an omission to do an act which must be done in order to prevent that result.
This English translation is provided for reference only and has not yet been firm-verified — always rely on the Thai original.
Firm annotation
Section 59 is the cornerstone of Book 1 on Criminal Liability, fixing the general rule that intention (mens rea) is required unless the law provides otherwise. Paragraph two defines intention as consciousness of the act coupled with either purpose as to the result or foresight of it, while paragraph three ties intention to knowledge of the facts constituting the offence, so a person unaware of an element cannot be treated as intending the result. Paragraph four defines negligence by an objective standard of care that the doer could and should have met, and paragraph five extends the concept of an act to culpable omissions where a duty to prevent the result exists. Every substantive offence in the Code is read together with this section, and it interacts closely with Sections 60 to 62 on transferred intent, mistake of person, and mistake of fact.
Why this matters in practice
In practice, Section 59 decides many cases before any offence-specific element is reached: if the prosecution cannot prove intention (or negligence where the offence allows it), there is no liability, and the burden of proving that state of mind beyond reasonable doubt rests on the prosecution. Because intention requires knowledge of the facts constituting the offence, a genuine lack of that knowledge is a core defence, and many offences also require a further special intent (for example a dishonest intent) that must be proved separately. Whether conduct was intentional, negligent, or neither is often the pivotal question, so early criminal law advice in Thailand should focus on the mental element.
Supreme Court decisions interpreting this section
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Supreme Court Judgment No. 4317/2567 (2024)
The intention to take another's property under Section 59 is distinct from the special dishonest intent required for theft; without dishonest intent there is no theft.
Applying the Section 1(1) definition of dishonesty, the Court held that dishonest intent is a special-intent element of theft in addition to the general intention under Section 59. Even where the defendant intended to take another's property, the absence of dishonest intent meant the conduct, done openly in daylight before witnesses, was not theft.
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Supreme Court Judgment No. 1732/2565 (2022)
Under Section 59 paragraph three, guilt requires that the doer knew the facts constituting the elements of the offence, and the prosecution must prove that state of mind beyond reasonable doubt.
In a bad-cheque prosecution, the Court held that the defendants could be guilty only if they knew, as an element under Section 59 paragraph three, that on the date of issue the account lacked sufficient funds. The prosecution bore the burden of proving that knowledge beyond reasonable doubt.
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Supreme Court Judgment No. 185/2566 (2023)
Liability for an intentional offence is tested by the Section 59 paragraph two definition of intention: consciousness of the act together with purpose as to, or foresight of, the result.
Where the defendant erected concrete posts and a barbed-wire fence across a public way, blocking vehicle access to the co-plaintiff's land, the Court framed the question of criminal intent squarely by reference to the Section 59 paragraph two definition of intention.
Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.
Frequently asked questions
What counts as acting intentionally under Section 59?
Intention means acting with consciousness of the act while either intending the result or foreseeing it. A person who does not know a fact that forms an element of the offence cannot be treated as having intended the result.
Can I be liable for negligence under the Penal Code?
Only where a specific offence provides for it. Section 59 defines negligence as failing to use the care a person in that situation should and could have used, but negligent conduct is punishable only when the law says so.
Can failing to act be a criminal act?
Yes. Section 59 paragraph five treats causing a result by omitting an act one was bound to perform to prevent that result as an act, so a culpable failure to act can attract liability.