At times the forensic handwriting examiner is called upon to be an expert witness. An expert witness is generally assumed to have the appropriate knowledge, skills and training and therefore expertise in a particular field. According to Dror (2011), this expertise is acquired through
repeated opportunities to apply knowledge and skills in a particular discipline and as time goes by, they become more discerning about what is relevant and what not.
As a result of knowledge and skills of forensic handwriting examination, it is the responsibility of the document examiner to provide the legal fraternity and others with facts, objectively and impartially.
This begs the question, ‘is the FDE obliged to ‘assist’ the client to prove their case? Categorically, no! The facts as obtained through objectively applied principles, may help or hinder their client’s case, but that is not something the FDE need concern him or herself with. The FDE is obliged to provide the court with unbiased facts to assist the judge to make an informed decision, whether it compromises the client’s case or not.
Now the question to the forensic document examiner is, ‘how accurate and unbiased is the forensic handwriting examination you conducted and the report you have written?’ Can we say with absolute certainty that what we have produced is 100% accurate? How does the FDE ensure an accurate report?
Well, it is not as easy as following principles such as outlined in the ASTM standards. The human element can easily interfere with objectivity and unfortunately as an expert witness, the forensic handwriting examiner (like expert witnesses in all forensic science disciplines), is also at risk of cognitive bias. Cognitive bias in forensic science can be defined as flawed judgement resulting from undue influence by people or circumstances during the course of a forensic investigation, giving rise to what Murrie et al (2009) refer to as adversarial allegiance.
A plethora of research has been conducted over the years suggesting that any and all scientists and forensic experts, are subject to bias to varying degrees. These biases take the form of expectation bias, confirmation bias, contextual bias, and many others.
Many prominent scholars have spent years attempting to find the elusive answer to a perplexing question, ‘how do we reduce or eliminate cognitive bias in forensic science?’
A number of ‘debiasing’ techniques have been put forward. These include providing minimal background information ( on a need to know basis) to the FDE to reduce contextual bias. Contextual bias occurs when the expert has access to background information and is influenced by it. The case is often presented to the FDE deliberately or inadvertently with bias-inducing information. This has been my own experience where the client begins at length to explain the scenario. For my own peace of mind and to keep my objectivity intact, I make it clear that I prefer not know the finer detail. Without too much background detail to the case, the FDE is then able to do a blind analysis.
Research (Murrie, et al, 2013) has shown that experts can be swayed by information about the case, such as whether they are ‘working’ for the defense or the prosecution. This implies that unconsciously they had preconceived ideas about offenders depending on which ‘side’ they were working for. Another form of bias is confirmation bias occurs when the expert ‘finds’ evidence to prove a point, which results in information being ‘identified’ which prove the case one way or another.
Perhaps a consideration is training in meta-cognitive awareness where the forensic expert, is taught to monitor and be aware of what and how they are thinking in order to self regulate their own biases. As explained by Symborski et al (2014, p2), ‘though cognitive biases are deeply ingrained and difficult to alter, knowledge of cognitive biases and bias mitigation strategies can help reduce the impact of cognitive biases on human reasoning.’ Symborski et al (2014) completed a study using a computer game to determine whether humans could be taught to control their cognitive bias. Their results showed positively that if adults are aware of the potential impact of cognitive bias on their work, the awareness could reduce cognitive bias.
Cognitive bias is a definite danger to the credibility of the forensic document examiner and it is incumbent on the document examiner to guard as far as possible against this enemy to their credibility.
Below an interesting read on confirmation bias.