Wrongful convictions occur surprisingly frequently but the Australian criminal justice system does not keep statistics. Based on extrapolations, especially from the UK which has had a Criminal Cases Review Commission for over 20 years, a recently published book estimates that in Australia there may be around nine instances per year, with most going unrecognised[1].

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There are multiple factors that can contribute to a wrongful conviction and usually more than one contributing factor can be identified in any particular case. Wrongful convictions are more likely to occur where a prosecution case is based predominantly on circumstantial evidence and where complex forensic or other technical evidence is contested among competing expert witnesses.

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The following list of potential contributing factors has recently been published[2]:

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“To summarise, the factors that have been widely reported to contribute to wrongful convictions are listed below. We have discussed the majority of these but not all.

• misleading or inadequate or poorly validated forensic science and other expert opinion evidence;

• tunnel vision and confirmation bias affecting police, expert witnesses and even courts;

• unreliable opinion evidence which then biases other evidence and its interpretation;

• police over-zealousness, incompetence or corruption;

• prosecutor misconduct, including failure to disclose exculpatory evidence; 

• false or coerced confessions, especially from vulnerable suspects;

• inappropriate reliance on police informants or prison informants;

• mistaken eyewitness evidence including misleading line-up identification procedures; 

• perjury by witnesses as well as perjury and/or negligence by criminal justice officials;

• ineffective, inexperienced or under-funded defence counsel;

• the reliance on juries to assess the validity and reliability of scientific and medical evidence;

• erroneous judicial directions to the jury;

• media pressure and/or stereotyping; and

• Indigenous ethnicity of the accused.

To this list we should add the difficulty that judges, barristers and juries may have in comprehending complex forensic or scientific evidence.”

 

[1] See Wrongful Convictions in Australia by Stephen Cordner and Kerry Breen. Australian Scholarly Publishing 2023.

[2] See Wrongful Convictions in Australia by Stephen Cordner and Kerry Breen. Australian Scholarly Publishing 2023.