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The Case Against DNA

Hugh Pickens writes "Thanks to fast-paced television crime shows such as CSI, we have come to regard DNA evidence as incontestable. But BBC reports that David Butler has every right to be cynical about the use of DNA evidence by the police. Butler spent eight months in prison, on remand, facing murder charges after his DNA was allegedly found on the victim. 'I think in the current climate [DNA] has made police lazy,' says Butler. 'It doesn't matter how many times someone like me writes to them, imploring they look at the evidence... they put every hope they had in the DNA result.' The police had accused Butler of murdering a woman, Anne Marie Foy, in 2005 — his DNA sample was on record after he had willingly given it to them as part of an investigation into a burglary at his mother's home some years earlier. But Butler has a rare skin condition, which means he sheds flakes of skin, leaving behind much larger traces of DNA than the average person. Butler worked as a taxi driver, and so it was possible for his DNA to be transferred from his taxi via money or another person, onto the murder victim. The case eventually went to trial and Butler was acquitted after CCTV evidence allegedly placing Butler in the area where the murder took place was disproved. Professor Allan Jamieson, head of the Glasgow-based Forensic Institute, has become a familiar thorn in the side of prosecutors seeking to rely on DNA evidence and has appeared as an expert witness for the defense in several important DNA-centered trials, most notably that of Sean Hoey, who was cleared of carrying out the 1998 Omagh bombing, which killed 29 people. Jamieson's main concern about the growing use of DNA in court cases is that a number of important factors — human error, contamination, simple accident — can suggest guilt where there is none. 'Does anyone realize how easy it is to leave a couple of cells of your DNA somewhere?' says Jamieson. 'You could shake my hand and I could put that hand down hundreds of miles away and leave your cells behind. In many cases, the question is not "Is it my DNA?", but 'How did it get there?"'"

9 of 166 comments (clear)

  1. Re:no cell phone evidence? by bigstrat2003 · · Score: 5, Insightful

    That would only prove where the phone was, not where the person was.

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  2. Phantom of Heilbronn by Anonymous Coward · · Score: 5, Interesting

    Contaminated DNA samples can even lead to imaginary super criminals:

    http://en.wikipedia.org/wiki/Phantom_of_Heilbronn

  3. Re:I Guess This Is What Happens When I Don't Watch by IAmR007 · · Score: 5, Insightful

    Plus, if they had any idea as to how science works, they would know that one datum doesn't constitute reliable evidence at all. Even finding the same DNA in multiple locations doesn't rule out systematic contamination. Multiple types of evidence are needed to confirm causation with anything. It scares me that people's entire lives can depend on methods that would get any scientist laughed out of the room.

  4. Re:no cell phone evidence? by alen · · Score: 5, Informative

    this is england but here in the US you need beyond a reasonable doubt. the cops can check the phone for prints and there is a record of movement by tracking every tower it hits. combine with CCTV evidence of stores and other cameras along with credit card transactions it should be fairly easy to show where you were

    i've been on a criminal case jury and we ruled not guilty in a half hour because the cops had a weak case

  5. Re:I Guess This Is What Happens When I Don't Watch by betterunixthanunix · · Score: 5, Insightful

    DNA should be used as one piece of a very large puzzle used to prove beyond a reasonable doubt that this person was present at some point in time

    Within some error margin, and that error margin is quite a bit higher than you might expect. If you do not exclude identical twins, even if there were no laboratory errors at all, the probability of finding two people with the same DNA profile would be 1 in 1000; when laboratory errors are included in the analysis, that probability can become high enough to pass the threshold of "reasonable doubt."

    Even if we assume no lab errors, no identical twins, and no measurement errors, DNA evidence is still not sufficient. I could plant someone's DNA at a crime scene without too much difficulty (consider how many personal items in your bathroom will have testable DNA on them -- a razor, a toothbrush, a comb). There have been cases of criminals finding ways to substitute another person's DNA for their own, including one case of a doctor who actually managed to hide another person's blood in one of his veins, thus faking his innocence.

    One data point is not enough to draw any sort of conclusion; it might point you in the right direction, but nothing more.

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  6. Re:I Guess This Is What Happens When I Don't Watch by Desler · · Score: 5, Insightful

    Why is an unrealistic American television show being referenced about a case in Liverpool by a UK news source? Is horrible American television that prevalent?

    Because you're being an intentionally obtuse pedant. First of all, the statement said 'shows like CSI' and if you think international crime shows don't use DNA evidence the same way you're quite naive. The specific show wasn't the point and the reason this is a problem is that popular culture shows has inflated DNA evidence as being some 100% accurate measure of guilt such that juries now will demand DNA evidence in order to even fathom the idea that the persn was guilty. Also, theynare easily misled by DNA evodence in wrongfully convicting people since they don't understand the probabilities or other curcumstances involved that could lead to the DNA being at the crime scene. Hell, The Independent in the UK wrote an article about juries being misled by DNA evidence back in 1994.

    Also, yes, CSI has aired internationally for many years with the U.K. being one of those places. Many American shows air internationally. That this is somehow news to you is hilarious.

  7. Re:I Guess This Is What Happens When I Don't Watch by Anonymous Coward · · Score: 5, Informative

    Here. He surgically implanted a vial of someone else's blood into his arm prior to taking the DNA test. He manipulated the collector to take it from his arm rather than the standard finger prick.

  8. Re:no cell phone evidence? by MachineShedFred · · Score: 5, Interesting

    The police will try to send any kind of weak shit that they can to the district attorney, because they can then mark the case solved and blame the DA or the Grand Jury should they fail to indict. The police commanders are happy because they get the closed case stats, the prosecutors stay happy because they don't take weak shit cases to trial, so their conviction rate stays up.

    Everyone else loses. The whole world shines shit and declares it to be gold.

    Also, this doesn't sound like a failure of DNA, this sounds like a failure of the detectives to properly interpret trace evidence.

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  9. Juries easy to sway by Sentrion · · Score: 5, Interesting

    Let's face it, our educational standards have dropped to such a low point that most juries in America can be swayed by any motivated and well funded prosecutor. There's enough DNA evidence to convince the average jury that I am in fact a Chimpanzee, just by showing them that I share 96% of chimp DNA. Prosecutors are quick to point out the difference between "shadow of a doubt" and "reasonable doubt" - 96% DNA clearly removes any 'reasonable' doubt that I am not a chimp. People have been executed in this country within the last decade with even flimsier evidence.

    Most murder suspects have to pay their life's savings and rack up additional years of debt to cover legal expenses while simultaneously losing earning opportunities, usually resulting in bankruptcy even if they are acquitted. Even when they hire an attorney they usually don't have the funds to put up an equivalent defense compared to state budgets. The cost of legal defense can devastate an entire extended family. When Brian Banks was falsely accused of rape his mother sold her house, car and went into debt to cover his legal expenses. He is an NFL hopeful with a goal to make enough money to pay back his mother. Not every falsely accused will have such an opportunity.

    Having a public defender appointed to represent you just means you get an under-paid, unmotivated lawyer that just wants to wrap up the case quickly with an admission of guilt or a plea agreement. But the state can spend $10 million on just one case in the name of being "tough on crime". Prosecutors have to win almost every case that goes to trial or force the accused to accept archaic plea deals. If they let suspects walk on lack of evidence it becomes front page news, and it damages their future prospects, especially if they seek election to a public office. The emergence of the Prison-Industrial Complex is one of the greatest present-day threats to our democracy and individual freedoms. Pray it doesn't happen to you.