Non-retroactivity is the organising premise of Maltese criminal law: liability attaches only to conduct that was already criminal at the moment it was carried out, and the State may not tighten penalties or expand liability after the fact. From that premise flows the principle of lex mitior: when the law applicable at trial differs from the law in force when the conduct occurred, the more lenient regime governs.
As Professor Anthony Mamo explained, “if the legislature cancels the criminal character of the act before the man is tried, there is no longer any justification for inflicting punishment upon him… the operation of the old law cannot extend beyond its repeal.” The principle is not a concession to mercy but the logical consequence of legality’s temporal limits: once a penal norm is repealed or softened, its harsher features do not outlive it; conversely, a milder later rule may be applied in favour of the accused because applying the earlier, stricter rule would give it effect beyond its valid life.
Continuity at the point of repeal is structured by the Interpretation Act. In substance, repeal does not, by itself, extinguish liabilities already incurred or proceedings already underway; investigations and cases may continue as though the repealing measure had not been enacted, unless Parliament makes a contrary choice in express transitional language. This savings logic often appears in reform texts through formulas preserving what has been done or omitted under the earlier framework, signalling that pending positions are not casually displaced.
The same statute draws a sharp line for delegated legislation: retrospective operation is never presumed and arises only where the instrument itself says so; even then, retrospective effect cannot be used to criminalise or aggravate liability for earlier conduct. Courts have read the statutory words “may be made to operate retrospectively” as permissive rather than automatic, so a bare change in subsidiary rules cannot be treated as retroactive without explicit language.
For practice, the method is straightforward and text-led. Counsel should begin with the words of the new measure: is there an express retroactivity clause, and if so does it regulate procedure or does it purport to create offences, widen elements, or raise penalties—which it cannot do for past conduct?
If the text is silent, prospectivity is the default and any claimed retroactive effect must rest on strict necessity, not convenience. Where two regimes compete across time, a favourability analysis should be undertaken to identify the overall milder framework and apply it to the accused.
Finally, savings or transition provisions must be read with care; in the absence of clear displacement, repeal does not erase accrued responsibility or live proceedings, but delegated rules cannot retrospectively construct or intensify criminal liability.
Punishment follows law – it never precedes it.
