Introduction: The Global Challenge of Double Jeopardy

The principle of double jeopardy — that no person shall be tried or punished twice for the same offence — is a cornerstone of criminal justice in many legal systems. Rooted in the ancient maxim nemo debet bis vexari pro una et eadem causa (no one should be twice troubled for the same cause), it protects individuals from government overreach, harassment, and the emotional and financial toll of repeated prosecutions. Yet as crime becomes increasingly transnational and legal systems interact across borders, the straightforward application of this right becomes deeply complex. A person acquitted for drug trafficking in one country may find themselves indicted again in another jurisdiction for the same conduct. International tribunals operate under their own rules, sometimes allowing retrials that would be barred domestically. This article examines how double jeopardy rights function across national boundaries, the treaty frameworks that seek to harmonise protections, and the significant legal challenges that remain.