The
ancient common law prohibition on multiple trials, known as the double jeopardy principle or its
Latin equivalent nemo debet bis vexari, is a procedural defence that prohibits
the prosecution of an accused for a criminal offence for which he has already
been acquitted or convicted following a trial on the merits by a court of
competent criminal jurisdiction. A
peremptory plea of autrefois acquit or
autrefois convict may be entered meaning
the defendant was formerly acquitted or convicted of the same (or substantially
the same) offence. When the pleas in bar
are raised, evidence will be placed before the court, which will normally rule
as a preliminary matter whether the plea is substantiated, and if it so finds,
the projected trial will be estopped. Double jeopardy can only arise when there
has been a previous criminal trial. In
many countries, the protection against double jeopardy is a constitutional
right while in others it is afforded by statute law.
Statutory
modification of the principle in England and Wales has been the model for
reform in several common law jurisdictions, which allow post-acquittal retrials
in limited circumstances where new and compelling evidence emerges or where
there acquittal is tainted. This paper
critically evaluates double jeopardy law reform in Ireland in the light of
reforms in England and Wales and possible implications for the trial of
offences in the Irish criminal justice process.