Forensic Science Doesn’t Provide Trustworthy Evidence

Forensic Science
Forensic Science
Forensic Medicine/Forensic Medicine & Toxicology

In this study Forensic science is under attack. A string of recent collapsed trials and quashed convictions that relied on forensic evidence have led some experts to say the field is in crisis. Several US and UK government reports over the last few years have highlighted and condemned failings in the use of forensic science. And there is an increasing rhetoric in the media against “junk” forensic science, an informal term used to condemn techniques not validated by a solid body of scientific research.

Among the public, the popularity of true crime documentaries exploring the role of forensics in potential miscarriages of justices, such as Making a Murderer or Netflix’s recent Exhibit A, may be encouraging the idea that forensic science doesn’t provide trustworthy evidence. But it’s not the science itself that is the issue. It is how it is misused by rogue scientists or misinterpreted by the police and the courts.

Validated forensic science

One example of a well established, highly validated forensic science technique is DNA profiling; so which involves comparing the DNA of a suspect to that find at a crime scene. DNA profiling is often referred to as the “gold standard” of forensic science. This is base not on the power of specific evidence; but the fact it is base on meticulously researched scientific principles and has thoroughly tested.

When DNA profiling was first use in the case of suspect rapist; also murderer Colin Pitchfork; so it underwent a baptism of fire, where the science was being challenge from all sides, legally and scientifically. But the evidence base on semen samples take from the victims’ bodies was deem watertight; also Pitchfork was give a life sentence. DNA profiling emerge as a virtually unchallengeable forensic science discipline in routine cases.

The challenge lies in non-routine cases. One episode of Exhibit A looks at “touch DNA”, a form of evidence that may be turn to if there isn’t a stronger source of DNA. It basically refers to small DNA samples transfer to other people or objects that someone has touched, often from skin cells from the palms of their hands. Touch DNA is typically find in very small amounts (less than 0.5 nanograms).

Matching DNA profiles

The documentary feature a case in which someone was beaten up by a large group of men; so one of whom pull off the victim’s shoe. Investigators recover what appear to be a matching shoe from a nearby roof; also create a profile from touch DNA found on it. This was the point when good science became bad.

One of the problems with forensic science, is that the courts require black and white answers; which science generally cannot give. This means that there is often pressure to reinterpret results in simpler terms; so leading evidence to be present as much more definitive than it should be. For example, a court may treat matching DNA profiles as conclusive proof that a sample came from a suspect when, as we know, there are limitations to this.

These kinds of miscarriages of justice base on misuse of evidence; so largely stem from a desire to see justice served. People who work in law enforcement or forensic science; which want to contribute to making their communities safer. In a high-profile or particularly horrific case, that emotional drive becomes a lot stronger. There is also a drive to be creative and innovative with the application of forensics.

This isn’t inherently a bad thing (it’s what fuels progress, after all); but there needs to be more of a practical acceptance of the limitations of the forensic science within the justice system. Without this, not only will there continue to be miscarriages of justice, but forensic science as a whole could be damage; so potentially leading to even more people being wrongly freed or imprisoned.