Forensic evidence can be very powerful in front of a jury and ultimately sway their verdict. In cases where forensic evidence is relied upon heavily by the prosecution, it can be devastating to the defence case unless it is dealt with and rebutted properly and effectively.
The Influence of Forensic Evidence: Weighing Science and Challenging Bias in Court
By virtue of its very nature, forensic evidence is complex and inevitably involves scientific concepts that can be challenging to properly understand, let alone explain. However, because forensic evidence is scientific, juries can afford it undue and significant weight. Without an experienced criminal defence lawyer present to rebut and challenge the science, and the conclusions the jury can draw from it (if any), this evidence goes unchallenged.
There is now a growing awareness of pseudo-science, scientific techniques and theories that are, in fact, unreliable and affected by a phenomenon known as confirmation bias. For example, there is a growing reluctance to introduce pattern-matching fields of forensic science into criminal trials because of the lack of proper scientific validation. These include tool mark examinations (examination and matching of firearms to projectiles) and bite mark examinations. In the case of bite mark examinations, there have been a number of exonerations based on DNA evidence which reveal that the people convicted could not have been the perpetrators (notwithstanding that the bite mark evidence introduced by the prosecution purported to prove that it was). Unfortunately, in some jurisdictions in the United States of America, these exonerations have occurred posthumously because the exoneree has already been executed for the crime.
Because of the weight and importance that juries can place on such evidence, criminal defence lawyers must skill themselves in their understanding of the evidence and the limitations of it. Even where compelling evidence exists, defence lawyers must be alert to how that evidence may have been created or contaminated.
Challenging the Reliability of Forensic Evidence for a Fair Trial
By way of example, our office represented a young man who was the passenger in a vehicle owned and driven by his friend and intercepted by police. The police officers intercepted the vehicle because they formed the view that it was acting suspiciously in a high drug trafficking area of Melbourne. Our client told police that they had just been out to dinner and that his friend was dropping him back home. When the vehicle was intercepted, both occupants were asked to get out of the car, which they did. One police officer then put on gloves and searched our client’s pockets. He then went to the front passenger seat and searched our client’s bag and personal effects, before going to the back passenger seat and searching a bag which was then found to contain a large amount of drugs. After DNA analysis was conducted, our client was charged with serious drug offences and remanded into custody based solely on DNA found on the bag of drugs, which the prosecution asserted was our client’s DNA. There was no other evidence of drug trafficking by our client at all. All charges were ultimately withdrawn when our office pointed out that the police officer who conducted the search did not change his gloves between searching our client, his belongings and then the bag of drugs. Accordingly, the low-level amounts of DNA found on the drug bag could have been transferred by the police officer, who did not change his gloves between searching our client and his belongings and then searching the bag.
Had the aforementioned case proceeded to trial, we would have argued that the judge should not allow the prosecution to lead the DNA evidence because it was so unreliable and the jury may afford it undue weight. It would render the trial unfair. Pre-trial hearings in relation to evidence are essential avenues by which forensic evidence can be ruled inadmissible by virtue of its unreliability. It is imperative that, if you are facing a trial where forensic evidence is relied upon, you speak with your lawyer in relation to whether there are any pre-trial arguments that can be made to avoid forensic evidence being considered by a jury.
The Value of Independent Forensic Experts in Strengthening Your Defence
In circumstances where the forensic evidence is being led by the prosecution and allowed by the judge, independent experts can be invaluable to assisting your defence to successfully cross-examine the prosecution expert and, also, potentially give evidence for the defence. We have found that independent experts are particularly useful in major collision cases where the prosecution case theory is that the accused person was driving dangerously, whilst the defence case is that the collision was simply an accident caused by external factors. Having an independent expert assess the calculations provided by police of speed and trajectory can provide an alternative case theory that, ultimately, debunks the prosecution case.
The law says that the prosecution must not only prove their case beyond all reasonable doubt, but that the jury has to be satisfied that there is no other theory consistent with innocence. In forensic cases, given how much weight jurors inevitably apply to forensic science, having an independent expert give evidence for the defence can make the difference between conviction and acquittal. Our team only engages the very best and most qualified forensic experts, whose credentials we check extensively and who have been used in successfully defended jury trials. Our team also constantly upskill their continuing professional development so that we are aware of the most recent forensic and technological developments in forensic science.
Engage Melbourne’s Most Experienced Criminal Lawyers
If you are charged with a serious criminal offence and the prosecution are relying on forensic evidence, you should consider contacting our office to arrange a consultation to discuss the nature of the evidence and how we can help you.
