Double jeopardy

In jurisprudence, double jeopardy is a procedural defence (primarily in common law jurisdictions) that prevents an accused person from being tried again on the same (or similar) charges following an acquittal or conviction and in rare cases prosecutorial and/or judge misconduct in the same jurisdiction.^[1] Double jeopardy is a common concept in criminal law – in civil law, a similar concept is that of res judicata. The double jeopardy protection in criminal prosecutions bars only an identical prosecution for the same offence except when the defendant is a servicemember as the courts have ruled that the military courts are a separate sovereign therefore servicemembers can be held in two separate trials for the exact same charges; however, a different offence may be charged on identical evidence at a second trial. Res judicata protection is stronger – it precludes any causes of action or claims that arise from a previously litigated subject matter.^[2]

A variation in common law countries is the peremptory plea, which may take the specific forms of autrefois acquit ('previously acquitted') or autrefois convict ('previously convicted'). These doctrines appear to have originated in ancient Roman law, in the broader principle non bis in idem ('not twice against the same').^[3]