New Zealand Law Society - Guide shows what DNA can do in criminal justice system

Guide shows what DNA can do in criminal justice system

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Researchers from the European Forensic Genetics Network of Excellence (EUROFORGEN) and the charity Sense about Science have issued a guide, Making Sense of Forensic Genetics, to show what DNA analysis can and cannot do in the criminal justice system.

The guide refers to landmark cases where DNA has been a gamechanger, and also looks at the limitations of DNA analysis - including where misinterpretation of DNA evidence has led to miscarriages of justice.

The researchers says it is important that the strengths and limitations of DNA profiling in support of criminal investigations and prosecutions are understood by all those involved in the criminal justice process as well as more widely in society at large.

Key points made by the researchers include:

Despite claims to the contrary, predicting visible traits such as face shape from DNA is not currently possible: The latest advances in forensic genetics are beginning to enable some externally visible characteristics including hair and eye colour to be predicted from somone's DNA. However, there are limits to what can currently be told from DNA.

Your DNA could be in a room even if you weren't: Our DNA is everywhere and it can be transfered by saliva from talking, sneezing, coughing and by shedding skin cells. There is even DNA present in house dust. So DNA from individuals who have nothing to do with a crime might be present at a crime scene.

DNA alone doesn't solve crimes: The presence of DNA doesn't establish guilt - and doesn't necessarily tell us when or how it got there or the body tissue it came from (particularly for very small amounts). Therefore, context has become increasingly key, and DNA needs to be viewed within a framework of other evidence. It's an important detection tool, but it's certainly not a detective.