Criminal law
Published on 25 June 2026
When the Criminal Code changes, it is tempting to assume that the latest version always governs. It does not. For conduct that has already taken place, the starting point is the law in force when it was committed. There is, though, an important exception in the defendant's favour: if the later law is more beneficial, it applies backwards. This is favourable retroactivity, the lex mitior.
This is brought into focus by Organic Act 1/2026 of 8 April, on habitual reoffending, which amended the Spanish Criminal Code (including articles 22 and 66) and came into force on 10 April 2026. When a reform of this kind affects matters based on earlier conduct, it is worth examining, case by case, which wording applies.
The Criminal Code provides that more favourable criminal laws have retroactive effect, even where a final judgment has been handed down and the person is already serving their sentence; and that, where there is doubt as to which law is more favourable, the defendant must be heard (article 2.2 of the Criminal Code). In practice, this comes down to three ideas:
The 2026 reform affected the aggravating circumstances (article 22) and the rules for determining the sentence (article 66), in particular the treatment of reoffending. With reforms that toughen the criminal response, conduct committed before they come into force will usually remain governed by the earlier wording, as the more favourable one. But that conclusion cannot be assumed: it has to be checked in each matter, because the same conduct, on the same evidence, may carry a different consequence depending on which wording applies.
Take a synthetic case. Someone is tried for a fraud committed in 2024. At the time, the law set a certain amount as the threshold above which fraud is treated as aggravated, carrying a higher penalty. After the conduct, a reform raises that threshold: conduct that previously fell within the aggravated offence now falls within the basic one, with a lower penalty.
If the amount in our example falls, under the new law, below the aggravated threshold, the defendant benefits: even though the conduct dates from 2024, the later wording applies because it is more favourable. The practical consequence is a lower sentence, and that benefit is granted even where a conviction has already been handed down, because favourable retroactivity reaches a final judgment as well.
The reverse also holds: if the reform had toughened the treatment (as happens, for instance, with habitual reoffending in 2026), earlier conduct would still be governed by the old, more lenient law. In both cases the rule is the same: the more favourable law applies, which is why the two versions must be compared with care.
This is where method shows. Before settling on a position, I check what the wording of the provision was on the date of the conduct and compare it with the version in force, to see which law applies and whether there is room for lex mitior. I check every citation against its official source, the BOE, and never take one as good without verifying it.
If you have criminal proceedings open over conduct predating a recent reform, it is worth knowing which law works in your favour. You can read how I handle criminal law matters or write to me for an initial assessment.
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