double jeopardy

Double jeopardy is a procedural defence that forbids a defendant from being tried again on the same (or similar) charges in the same case following a legitimate acquittal or conviction. In common law countries, a defendant may enter a peremptory plea of autrefois acquit or autrefois convict ( means "in the past" in French), meaning the defendant has been acquitted or convicted of the same offence and hence that they cannot be retried under the principle of double jeopardy.