Forensics is a universal science, traversing the entire spectrum of various diverse fields. As a profession, in the 21st century, it has taken root in today’s society though with different levels of advancement, protocols and policies in different jurisdictions. May the listed principles serve as a curtain raiser or some sort of refresher for the new and the old guard in the forensics field?
- Law of individuality: Every object, artificial or otherwise is unique. Although from a distance, objects of the same morphology, class etc. may seem the same, the devil is always in the details. Fingerprints, DNA may all be similar but they are distinctly unique.
- The exchange principle: Commonly known as Edmond Locard’s maxim on interchange “that a person or persons at a scene where a crime has been committed will almost always leave or take something away”
- Law of progressive change: You’ve probably heard of the saying “Change is inevitable”. Well this also applies to objects although it may take different objects different time spans. Bodies decompose, tire tracks & bite-marks fade and the list goes on and on…
- Law of comparison: Samples can only be compared to like samples; be it reference, questioned or control samples. A questioned hair can only be compared to another hair sample, same with tool marks, bite marks, DNA…
- Law of analysis: An analysis can be no better than the sample under analysis, its chain of custody, its handling and the person analysing it.
- Law of probability: Forensics is all about percentage chance. All conclusions derived after an analysis are dependent on method used and their accompanying advantages & shortcomings which are all factored in the end result.
- Law of circumstantial facts: Man (Eye witnesses, victims) when giving evidence may not always be accurate. They may intentionally lie or many have shortcomings e.g. poor senses (sight, hearing…), exaggeration and assumptions. However, evidence which in turn provides a factual account has a higher percentage chance of accuracy and therefore highly reliable.