The common belief rests on a premise that forensic sciences are very exact and cannot be doubted. Facts relating to fingerprinting, DNA analysis and other particle matching were thought to be undeniable for a long time, but there are cases where seemingly factual information turns out to be wrong.
The television shows that illustrate the work of a crime scene investigation unit are often misleading and simplified. The process of identifying and matching a piece of evidence to a particular person is a long process which requires exact sciences and methods. Scientific theories are thought to be the most infallible pieces of knowledge, but the investigation is still done by people. As such, there is always a possibility of human error that can or cannot be predicted. When there is a matching of fingerprints shown on television, it is usually done on a computer where the machine visually looks through a database and then imprints one print on the other to find a match.
In the real world, experts do the matching by hand and it is a rather meticulous process. The general belief is that no person’s fingerprints are exactly alike someone else’s, but there is still a fraction of doubt. Unfortunately, in almost one hundred years of using the fingerprint technology there were no specific scientific studies done that would confirm the statement about the unrepeatable uniqueness of a fingerprint. An investigator would rely on their experience and personal knowledge when looking for a match, as there needs to be several points of similarity. Previously, it was thought that 7 to 10 or 15 points have to be alike in order to determine a match. Presently, this has become too little to make a positive decision because mistakes can be made with the lower number of matching points. Another problem is if there is a partial fingerprint where some parts are missing, so the expert has to “fill in” the gaps and make “a leap of faith” in deciding if there is a match.
A similar trend has emerged with other matching techniques, such as hair follicles and bite marks. There were numerous cases where people were wrongfully convicted or even executed based on unsupported evidence. It is noted that the judges and jury are not experts, so they have to rely on expert testimony which is done by forensic units, doctors and scientists. Currently, such testimony is not taken as a hundred per cent infallible because of the human error and lack of scientific support. It has also been shown that people are cognitively predisposed to make a certain decision, basing it on an unconscious bias. This usually happens in relation to the specific details of the case where evidence seems to point to a certain person or direction. It has been suggested that the scientific method is correct only because it was not disproved for a long time, and one of the judges correctly mentioned that if something was done wrong for a long time and there was no evidence to counter the wrongdoings, the amount of time does not make a wrong right.
In conclusion, it has now been realized that CSI is not as exact and infallible as previously thought. Judges and jury now know not to fully rely on seemingly scientific evidence produced by forensics.