https://github.com/davepinch/pinchy.cc/blob/master/content/topics/government/united-nations/universal-declaration-of-human-rights/clauses/12.md
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.