1 What is forensic science?

Forensic science is often described as the science that is used to resolved a legal dispute. It might be better, and more officially, thought of a case-based endeavour brings a scientific and research-based approach to study traces of a past activity, such as the presence of a person and their actions. This is undertaken through many steps, including detecting, recognising, and recovering trace materials, comparing them with other traces that are recovered, interpretating and evaluating what they mean in relation to the crime and communicating the meaning of the traces to the police, the courts and possibly the public.

The Sydney declaration (Roux et al, 2022) provides seven principles underpinning forensic science. These help in the practice, research and education of forensic science. This is important because practitioners need to be learning what and how to do their jobs and the public need to know that the scientists have the training and expertise to be trusted. The principles are, put simply:

1. What people or criminals do and where they do it can leave traces which can be followed up in an investigation.
2. Scientists collecting evidence at a crime scene need to have specialist training and need to treat crime scene work as a true science.
3. Each case is different, but forensic scientists will apply their scientific knowledge to each case systematically to draw their conclusions.
4. Forensic scientists need to consider what happens in the commission of a crime, and the possible time lag between the activity and the trace evidence being discovered and analysed.
5. It is often hard to state forensic science findings with absolute certainty so forensic scientists have to be prepared to work with some uncertainty.
6. Forensic science can contribute to many aspects of criminal justice including investigating and providing evidence to help prove innocence, or guilt.
7. Forensic science work only has meaning when it is viewed in the context of the specific investigation or crime. You cannot necessarily lift findings from one case and apply them to another. Each case has its own unique features.

The purpose of the Sydney declaration is to emphasise the importance of forensic science and the scientist from the beginning of the investigation – at the crime scene all the way through to its end in the courtroom.