The final part of this literature review draws on the preceding section as it sheds light on the issue of presenting this new three-dimensional evidence both digitally and physically in a criminal justice context. The main focus lies on the evidence presentation before a court of law. This stage is primarily concerned with visualisation, whereas the analytical benefits are more likely to be incorporated in expert witness statements such as the pathologist’s testimony. But even the presentation of the pathology results, which is a generally accepted part of any murder trial, can benefit from enhanced visualisation methods. Pathological and medical evidence in general tends to be very graphic and gruesome making it unsuitable for display. The resulting lack of visual representations makes it more difficult for a jury to understand the testimony and might result in a very dry oral testimony during which jurors might lose attention to the trial (Feigensen 2010). Using medical image data to illustrate the expert’s opinion has a long-standing tradition. First X-ray films were used, followed by digital X-ray images, CT and MRI data, and all faced initial opposition but quickly became generally accepted (Golan 2004). The main advantages of these images are that they show the jury images which would otherwise remain hidden and for which they would only have the expert’s word for. Additionally, the images tend to be grayscale representations of certain body regions which adds a level of abstraction that reduces the emotional impact and allows the fact-finder a more reasoned decision (Whalen and Blanchard 1982). Saunders et al.
(2011) briefly present the approach taken by pathologists in Leicester who were able to show scan data and 3D reconstructed models, run in real time from a laptop. This approach has the benefit that it is interactive and shows both cross-sectional and three-dimensional views and further demonstrates the court-readiness of medical imaging. However, the standard procedure (at WMP) tends to be body mapping where the injuries sustained by the victim are digitally mapped onto a dummy model which can be shown within the crime scene for additional context. The problem with this approach is that it only shows external injuries.
Many researchers have explored how this can be achieved more accurately and incorporating medical imaging data to display internal injuries as well (Urschler et al. 2012).
This is where digital 3D technologies have demonstrated great promise as different data sets can be aligned for a complete picture. External surfaces can be documented using different laser scanning technologies or photogrammetry for a more photorealistic view. Internal features can be illustrated using CT or MRI data, either as 2D sections or as volume-rendered view. The decision which option to choose depends on the degree of realism intended which reverts back to the issue of jury bias discussed in the previous chapter.
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The topic of 3D visualisation in the courtroom has received increasing attention with the introduction of computer simulations and animations, not only for their impact but also for admissibility issues. While it is sometimes argued that visual supplements which are used as demonstrative evidence at trial might be subject to lower admission standards (Campbell et al. 2013), medical imaging often fulfils the purpose of demonstrative as well as substantive evidence (Harston 2008). Both the image acquisition and its visualisation must therefore be validated and well documented. Validation is particularly important for computer animations and simulations. Moving computer graphics can easily be perceived as reality if the underlying principles and data used to generate the simulation have not been explained sufficiently. Jury members might misunderstand the animation or simulation as a depiction of the event rather than an illustration of the expert’s opinion thereof or one of the possible explanations (Schofield 2017). As with the depiction of medical evidence, the question is how much realism is necessary to maintain credibility but how much is too much, creating an overly easy-to-believe clip. The latter might be in the interest of the prosecution but goes against the principle of equality of arms as most defendants do not have the means to have such advanced computer graphics produced.
One final consideration is that courtrooms might not be equipped to display images that require specialist viewing software. The previous chapter presented the challenges the courts face and one is the slow adoption of technological innovation even on a basic level.
This limitation can bring many ambitious projects to an abrupt end. Tung et al. (2015) present an example of advanced 360 degree spherical photography being shown to jurors which required specialist viewing technology. This arguably improved the evidence presentation but is difficult to implement on a wider scale, simpler solutions such as the one presented by Saunders et al. (2011) are therefore recommended. While their benefits seem widely accepted (Ma et al. 2010, Tung et al. 2015) with excellent examples demonstrating their feasibility, it is likely to take some more time for these tools to become a regular choice in the advocate’s toolkit.
4. Summary
This third chapter presented Computed Tomography and more specifically micro-CT which is used in this research project and discussed their advantages and disadvantages. With reference to the gaps identified in the previous chapter, the present chapter demonstrated how the Criminal Justice System could profit from the use of digital tools. Some examples of
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their application in a forensic context were provided, however, such examples are limited and often based on experimental setups rather than actual case series. Furthermore, none of these cases provide a quantification of the impact created thus highlighting the need for more detailed analyses.
The next chapter will take the information provided in the two review chapters to develop a suitable research methodology based on more refined research questions.
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