Section 3 — More favourable subsequent law
English translation
If the law in force at the time of the commission of the offence differs from the law in force afterwards, the law that is more favourable to the offender shall be applied, in whatever respect, except where the case has become final, as follows:
(1) If the offender has not yet undergone the penalty, or is undergoing it, and the penalty fixed by the judgment is heavier than the maximum penalty under the law enacted afterwards, the court may, if it thinks fit, fix the penalty anew according to the law enacted afterwards; in so doing, the penalty already undergone by that person under the original judgment shall be deemed a penalty under the new judgment.
(2) If the court has sentenced to death, and under the law enacted afterwards the maximum penalty for that offence is changed to another penalty, the death penalty under the judgment shall be deemed changed to the highest penalty fixed by the law enacted afterwards for that offence.
This English translation is provided for reference only and has not yet been firm-verified — always rely on the Thai original.
Firm annotation
Section 3 governs the change of law where the offence remains an offence but the applicable penalty differs, complementing Section 2, which covers outright abolition. The core rule is that the more favourable law applies in whatever respect, so the offender takes the benefit whether the change touches the definition, the penalty range, or ancillary consequences. The two numbered paragraphs create narrow exceptions to the finality of judgments: paragraph (1) lets the court re-fix a penalty that exceeds the new maximum, on motion, and paragraph (2) automatically converts a death sentence to the new maximum. Because these are exceptions to finality, courts read the re-sentencing power strictly: it applies only where the final penalty is genuinely heavier than the ceiling of the later law.
Why this matters in practice
This is one of the most practically used general-part provisions, especially after major reforms such as the Narcotics Code replacing the older drugs law. A person already convicted can file a motion under 3(1) to have the penalty re-fixed to the lighter regime, but only if the final penalty actually exceeds the new maximum; a court will refuse the motion where that threshold is not met. The benefit is not automatic across the board: the more favourable law applies in whatever respect, but the exceptions to finality are limited to what paragraphs (1) and (2) allow. If a sentence was imposed before a favourable amendment, it is worth checking whether a re-sentencing motion is available.
Supreme Court decisions interpreting this section
-
Supreme Court Judgment No. 875/2568 (2025)
Re-fixing a penalty under Section 3(1) is available only where the penalty imposed by the final judgment is heavier than the penalty fixed by the later law; otherwise the motion must be refused.
In a narcotics case, the Supreme Court considered whether there were grounds to re-fix the defendant's penalty under Section 3(1) and confirmed that the power applies only when the final penalty exceeds the ceiling of the later law.
-
Supreme Court Judgment No. 7422/2568 (2025)
Where the penalty under the law in force at the time of the offence differs from and is heavier than the penalty under the later law, Section 3 requires the more favourable later law to apply in whatever respect.
The Supreme Court held that because the penalty under the old narcotics law was heavier than that under the new Narcotics Code, the more favourable new code applied under Section 3, and re-fixing the penalty accordingly did not offend the legality principle.
-
Supreme Court Judgment No. 434/2568 (2025)
A motion to re-fix a penalty under Section 3(1) requires that the penalty fixed by the final judgment be heavier than the penalty provided by the later law.
The Supreme Court, in a narcotics case, restated that re-fixing a penalty under Section 3(1) is confined to cases where the final penalty is heavier than the penalty set by the later law.
Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.
Frequently asked questions
Can my sentence be reduced if the law becomes lighter after I am convicted?
Possibly. Under Section 3(1) you can ask the court to re-fix your penalty under the newer, lighter law, but only if the penalty in your final judgment is heavier than the maximum penalty the new law allows.
What is the difference between Section 2 and Section 3?
Section 2 applies when a later law abolishes the offence entirely. Section 3 applies when the offence still exists but the law differs, in which case the more favourable version is used.
What happens to a death sentence if the law later removes the death penalty for that offence?
Under Section 3(2), the death sentence is deemed changed to the highest penalty that the later law fixes for that offence.