No one shall be held guilty of any criminal offence on account of any act or omission which did not constitute a criminal offence under national or international law at the time when it was committed.
Chumhdaigh an Chúirt Bhreithiúnais an ceart sin ina breithiúnas an 15 Bealtaine 1986, mar phrionsabal ginearálta de dhlí an Aontais (Cás 222/84, Johnston [1986]) ECR 1651; féach freisin breithiúnas an 15 Deireadh Fómhair 1987, Cás 222/86, Heylens, [1987] ECR 4097 agus breithiúnas an 3 Nollaig 1992, Cás C-97/91 Borelli [1992] ECR, I-6313).