DNA Should be Used to Exonerate Not Implicate
In response to my article Contrary To Popular Belief, DNA Profiles Are Not Absolutely Unique I know that someone will ask me, "If DNA is so unreliable why are you willing to accept it to exonerate someone but not to implicate someone?"
The answer is simple: no police officer or prosecutor is going to plant evidence that someone is innocent. That is to say, there is nothing to gain, no career to advance, to go back to a 20 year-old rape kit or semen or hair sample and switch it to prove that the person they prosecuted was in fact innocent.
In addition, while it is remotely possible that an accused person has virtually the same DNA as the real murderer, if DNA evidence shows that you are not the person who committed the crime then it is 100% certain that someone else committed the crime. Let me give you an example:
Assume for a moment that DNA is somewhat like a birth-day. Let us further assume the victim, before he died, wrote that he was killed by a person born on 7 Mar 1945 at 9:45 am. Let's say I was arrested for murder solely on the fact that I was born on that exact day and time. It is possible that there exists another person who was born on that exact same day and time. This is why I take DNA evidence to implicate someone in a crime with a big grain of salt.
On the other hand, let's say on re-examining the note left by the victim we find out that the policeman who read the note forgot his reading glasses that day and the actual birthday of the killer is 17 May 1954 at 9:45 am. Since it is impossible for me to have that birthday, it is obvious someone else is the killer. This is why I view DNA evidence as reliable in exonerating someone.
This is not just my opinion:
Wrongful Convictions Blog, 7 May 2012, Implicated by DNA, Exonerated by DNA – The Ashikaga Case
I once had a conversation with a retired judge in Japan. He said that although there seems to be a strong belief that the DNA testing is a new golden solution, he thinks we still need to be careful. He suggested that the fact that there was a “match” of DNA evidence found at the crime scene (or from the body of the victim etc.) alone should be used to exonerate someone, but not to implicate someone.
... there is a very well known case in Japan (Ashikaga Case) where a man was implicated by faulty DNA evidence and later exonerated by more sophisticated DNA evidence.
Photo Caption: Sugaya was released in 2009 after 17 and a half years of wrongful incarceration.
