One of the oldest principles in law, not just in Australia, but around the world, is double jeopardy, but as Perth Criminal Lawyers will tell you, despite it being around for so long, there remains lots of confusion regarding what it means.

In the simplest terms, double jeopardy is the legal principle that means once someone has been found not guilty in court for a crime, they cannot be retried for the same offence.

One of the primary reasons it was introduced in many jurisdictions was to prevent the crown, or the state, retrying the same person repeated times in the hope that eventually they would find a jury that was prepared to convict via a guilty verdict.

The issue of someone’s human rights being overridden by a determined prosecution convinced of that person’s guilt deliberately charging them again and again with the same offence was another reason double jeopardy laws were created.

Unless someone has been subject to double jeopardy, either as the accused or a victim, it is highly unlikely they will have even heard of the term, at least not with regards to legal matters.

In popular culture, the 1999 film called ‘Double Jeopardy‘ which starred Tommy Lee Jones and Ashley Judd, did somewhat bring it to people’s attention. The storyline involved a wife wrongly convicted of the murder of her husband, only for her to discover that he had staged the whole crime.

It continued with her being told after she had been released on parole, that if she did actually kill him, she could not be convicted of the crime a second time, and in effect, get away with murder.

Although fictional, this type of scenario, plus those where obvious miscarriages of justice took place where the guilty person seemed to be getting away with a crime, once new and compelling evidence against them had been uncovered, led to many questioning whether double jeopardy should continue as a legal principle.

Perhaps the most famous example in Australia is the case in 1973 of Dierdre Kennedy, who was a toddler taken from her bed whilst her sister slept beside her. Thereafter she was beaten, sexually assaulted, and strangled, with her body found on the roof of a toilet block.

12 years later, Raymond John Carroll was tried and convicted of her murder, with one of the main pieces of evidence being bite marks on Deirdre Kennedy’s leg, that matched Carroll’s dental records. His legal team lodged an appeal, which they won, and he was released.

Another 11 years passed before the police were able to use new forensic processes which once again provided conclusive evidence that Carroll was the perpetrator, but under the double jeopardy principle, he could not be retried for the crime, regardless of how compelling the new evidence was.

An attempt was made to try Carroll for perjury, but it ultimately failed at the high court, where the judge decreed that the entire process was an attempt to abuse the legal system.

Given the horrific nature of the Kennedy murder, and the failure to convict Carroll, despite the evidence against him, a public outcry led to many jurisdictions in Australia altering their double jeopardy laws, albeit not all did.

The changes meant that the most serious of crimes, such as murder could be retried in certain circumstances but there are various strict guidelines such as the production of fresh new evidence and that a retrial would be considered in the interests of justice.