Double jeopardy is a procedural defence that prevents a defendant from being tried twice on the same or similar charges after they have been acquitted or convicted.
Autrefois convict and autrefois acquit are principles of double jeopardy.
In many countries the guarantee that you can not be convicted of the same offence twice is a constitutional right. This is not the case for Australia however, Australian double jeopardy laws have been held to extend to the prevention of prosecution for perjury following a previous acquittal where a finding of perjury would invalidate the previous acquittal. A case on this point is R v Carroll.
Because of these inconsistencies many people have called for reforms of the law, and in some states legislation has been introduced to change some major aspects of the double jeopardy principle. In NSW retrials of serious cases with a minimum sentence of 20 years is now possible in certain situations.
South Australia doesn’t appear to have made any changes however discussions continue and reform is a possibility for our state as well.