Science and Law – Part 0

April 25, 2007

In the Journal of Law, Medicine & Ethics, Volume 34, Number 2, there’s an article titled “Just evidence: The Limits of Science in the Legal Process”, written by Sheila Jasanoff. It talks about the reliance on science in the legal process. What follows is a summary, with some short notes added.

It starts with an introduction about the Massachusetts governor, who tried to reintroduce the death penalty, mainly because science would produce failsafe/infallible results. Science produces a lot of facts, and with the help of the self-corrective nature of science, the reliance on those facts is high. Peer reviews are important in this respect. Organized skepticism, communalism, universalism and disinterestedness are important notions in the science community, as noted by the sociologist of science Robert K. Merton.

The law and science have different frameworks, different contexts, for producing facts. Therefore, the law shouldn’t always defer to “science’s overriding commitment to self-correction”. Trial judges should act as “surrogates for the scientific community in determining admissibility”. This isn’t a perfect solution, however. For example, in the post about the Monty Hall problem, there were a lot of math professors who didn’t agree with the solution. When science ultimately decides about someone’s life or death, these failures can’t be tolerated.

Science can’t proceed the same way in the courtroom, as it would outside it. It simply can’t remove the uncertainty that the law itself would have when convicting/judging a suspect.

DNA and Truth-Telling

Science may be a social activity, but when executed correctly, the results are viewed as no longer bearing traces of human subjectivity.” Because of the removal of human elements, the facts that are produced by scientists, are very reliable kinds of evidence. The transition from the subjective legal definitions to more objective scientific notions, through the removal of fallible human interpretations in criminal law through diagnostic instruments, is a process we already see happening with the advance of DNA technology. “The hope is that technology, through its mechanical reproducibility, will be impervious to context and will provide unbiased and reliable evidence about the facts of the matter.” Again, DNA technology is a good example. The enormous discrimination possible with DNA (random match probabilities of 1 in a billion for a complete profile) are negligible with respect to the chance a mistake is made by a human factor: problems with taking samples, mixed up profiles, contamination, holes in the chain of custody, etc. Those factors are far more likely to occur, and illustrate that an overreliance of DNA profiles is dangerous. Also, the human element in the law, and the urge of the public prosecutor to convict somebody (e.g. bias), are noteworthy components that shouldn’t be forgotten. The ability of DNA to establish identity is not questioned; it’s the interpretation of the results that should be questioned. Alternative explanations, no matter how unlikely, should all be removed before there’s a certainty for a rightful conviction.

Three more propositions will be investigated:

  • Truth-seeking in science is equivalent to truth-seeking in the law” (See part 1)
  • Law enforcement (or forensic) science establishes the truth as reliably as science in pure research contexts” (See part 2)
  • Genetic science is a particularly dependable source of truth, especially in disputes concerning human identity” (See part 3)



  1. Aye, humans are very prone to pass judgement. It’s human nature I suppose. The interpretation of every person varies.
    Even if you have a good and correct outcome of a DNA profile, you can indeed be looking at a wrong sample.
    That’s why it’s never 100% clear. Not even when there are witnesses, a confession, DNA matches and wot not. Coincidences still happen and hopefully technology will make the chance of a wrong conviction less likely.
    Go science!!! xD

  2. […] 26th, 2007 by nullify -Read part 0 here […]

  3. […] 28th, 2007 by nullify -Read part 0 here […]

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