In terms of international law, the Article 11 of the Universal Declaration of Human
Rights (UDHR) (1948) gives a very well structured definition of the principle: “No one shall
be held guilty of any penal offence on account of any act or omission which did not constitute
a penal offence, under national or international law, at the time when it was committed. Nor
shall a heavier penalty be imposed than the one that was applicable at the time the penal
offence was committed”