When a judge mitigates a prison term on optional grounds, must both limits be halved? Supreme Court Decision 2018Do5475 on 'optional mitigation'

Question

Article 25(2) of the Criminal Act provides that 'the punishment for an attempted offence may be mitigated compared with the completed offence', and legal mitigation is carried out by the methods in Article 55(1), of which item 3 provides that 'when imprisonment or confinement for a fixed term is mitigated, it shall be one half of the term'. Where the statute says the punishment 'may be mitigated' rather than 'shall be mitigated', the question is whether the judge is free to decide against mitigation, and, if the judge mitigates, whether the whole term, both its maximum and its minimum, is halved.

Decision 2018Do5475, a full-bench judgment of 21 January 2021, raises that question on an indictment for assault and attempted special injury. The first instance court had halved both limits of the statutory term for attempted special injury before applying concurrence aggravation, and the defendant appealed the first instance judgment on the ground of excessive sentence; the case also put in question whether halving both limits on optional mitigation was wrong, so that the validity of the current interpretation of optional mitigation itself was the issue.

Material to check

The statutes are Article 25 of the Criminal Act on attempted offences, Article 55 on legal mitigation, listing for each kind of punishment how the reduction is made and adding in paragraph 2 that where there are several grounds for legal mitigation the mitigation may be repeated, and Article 56 on the order of aggravation and mitigation, which runs: aggravation under the special provision, aggravation under Article 34(2), recidivist aggravation, legal mitigation, concurrence aggravation, and mitigation on grounds for leniency. Also cited are Article 1(1), under which the existence and punishment of a crime follow the law in force at the time of the act, Article 257(1) on injury and Article 258-2(1) and (3), under which carrying a dangerous object and committing the offence of injury is punished by imprisonment of not less than one year and not more than ten years and its attempt is punished, and Article 12(1) of the Constitution, the source of the principle of legality cited through the decision's reasons.

The decision cites, as the source of the current reading, Decision 91Do985 (11 June 1991), 2005Do6120 and 2014Do15131, whose text was not opened for the latter two. It relies on Decision 2017Do14609 (18 April 2019), a full-bench judgment which held that Article 55(1) applies to the reduction of concurrent offences under Article 39(1) for an offence under the latter part of Article 37, so that a fixed term of imprisonment cannot be reduced below one half of its length, and it also refers to Decisions 2006Do8376 (11 September 2008), 91Do985 and others on the stages of sentencing and on judicial mitigation under Article 53.

Possible readings

Read with Article 55(1)3 and the decision, the phrase 'may be mitigated' leaves the judge a choice: unlike necessary mitigation, where the grounds must be given effect once found, optional mitigation allows the judge to mitigate or not to mitigate, since 'may' carries within it the meaning 'may not'. The decision holds that this reading is the natural one in ordinary language, matches the statute and the legislature's intent, and so is not an analogy to the disadvantage of the accused prohibited by the principle of legality.

Once the judge does mitigate a prison term, the second reading fixes the method. Article 55(1)3 speaks of halving 'the term', which on its words means both the maximum and the minimum of the statutory range, not one of them alone. The decision adds that the range of the sentence fixed by law is the final standard for the sentence imposed and must be set strictly by statute, so no reduction of a different kind may be recognised unless an express provision provides for one, and it cites Decision 2017Do14609 for that point. Reducing only one limit, or reducing by more than one half, is therefore impermissible under the principle of legality.

A third point comes from the distinction the statute draws between the two kinds of mitigation grounds. The decision observes that necessary and optional grounds are separately enacted and their legal effects must be clearly separated as well: abandonment of an attempt under Article 26 is a necessary ground, while a frustrated attempt under Article 25(2) is optional, and the difference between the offender who turns back and the one whose plan fails only for external reasons should be reflected in the law. A uniform effect for every optional ground is not required.

What the decisions held

Decision 2018Do5475 held that the current interpretation of optional mitigation remains valid: the judge may choose whether to apply legal mitigation under Article 55(1), and, where the judge mitigates a prison term, both the maximum and the minimum of the term are halved under Article 55(1)3. It added that the practice of not mitigating unless the floor of the sentencing range needs to be lowered is not unlawful, that the judge's discretion here sits among the wide discretions given in sentencing, from the choice of punishment to judicial mitigation under Article 53 which comes last, and that the need and the means of controlling that discretion are a separate question. It dismissed the appeal.

The facts were these. The defendant was charged with assaulting Non-party 1 on about 23 December 2016 and, the same day, stabbing Non-party 2 in the chest with a kitchen knife, a dangerous object, so that only Non-party 2's clothing was torn when he pushed the hand away, leaving the offence at attempt. The first instance court convicted him of assault, selecting imprisonment, and of attempted special injury under Article 258-2(3) and (1) and Article 257(1), the statutory range being not less than one year and not more than ten years. It then mitigated under Article 25(2) and Article 55(1)3, producing a range of six months to five years, applied concurrence aggravation to that offence, and, because aggravating its maximum by one half would give seven years and six months while summing the maxima of the two offences gave seven years, fixed the sentencing range at six months to seven years, and sentenced him to eight months' imprisonment, suspended for two years, with probation and 120 hours of community service. The court below, the Uijeongbu District Court's judgment of 27 March 2018 (2017No3162), dismissed his appeal.

On those facts the decision held that halving both limits before the concurrence aggravation was lawful. The further complaint that the court below had failed to reflect a settlement with Non-party 1 was in substance an argument of excessive sentence, and under Article 383(4) of the Criminal Procedure Act that ground is admissible only where death, life imprisonment, or imprisonment or confinement of ten years or more has been imposed; since a lighter sentence was imposed here, neither that complaint nor the request to reduce the probation and community service order was a lawful ground of appeal.

Points left open

The decision leaves the exercise of the discretion itself largely unregulated. It holds that the judge may decide against optional mitigation, that in doing so the judge will necessarily consider other sentencing factors and may form a rough picture of the sentence, and that a practice of declining mitigation where the floor need not be lowered is not unlawful, but it states expressly that the need for and the method of controlling the discretion are a separate problem, and it sets no standards for its review.

The objections raised in the separate opinion of Justice Lee Ki-taek, who read optional mitigation as reducing only the minimum by combining the mitigated and unmitigated ranges so that one sentencing range is fixed automatically, are left undecided. They include the clarity of the sentencing range for the accused, the treatment of an argument that fails to produce any reduction, the appeal route against a sentence set at the floor of an unmitigated range, gaps that the current practice leaves between the lowest and highest sentence available, and the effect of the 2018 amendment, noted in that opinion, which turned mitigation for diminished mental capacity from necessary into optional.

When to reconsider

We revisit this brief if the Supreme Court adopts the position of the separate opinion and halves only the minimum of the statutory range, if Article 25 or Article 55 of the Criminal Act is amended, or if a later decision sets standards for reviewing the court's choice not to mitigate on optional grounds.

Statutes referred to

• 헌법 제12조
• 형법 제1조, 제25조, 제55조, 제56조, 제257조, 제258조의2

Decisions referred to

• 대법원 2021. 1. 21. 선고 2018도5475 전원합의체 판결 · Decision ledger
• 대법원 1991. 6. 11. 선고 91도985 판결
• 대법원 2019. 4. 18. 선고 2017도14609 전원합의체 판결 · Decision ledger

Verification status

All texts were read at the National Law Information Center on 24 October 2026. The decision was read in its published summary, holdings, cited provisions and precedents and full reasons, the cited articles in their current text as published, and the cited decisions in their published summaries and holdings where the text could be opened.