PCAST in the news – The DNA Blog from the New York Legal Aid Soc

Edited by Julie Fry
Written by Celia Givens

PCAST report raises questions about validity of forensic sciences in criminal courts


A new draft report from the President’s Council of Advisors on Science and Technology (PCAST) has caused concerns about the use of modern forensic science techniques in the criminal justice system, stating: “It has become increasingly clear in recent years that lack of rigor in the assessment of the scientific validity of forensic evidence is not just a hypothetical problem but a real and significant weakness in the judicial system.”

The report acknowledged PCAST’s concerns with the lack of agreement in the scientific community in analyzing complex DNA mixtures, noting: “Subjective analysis of complex DNA mixtures, including with the widely-used Combined-Probability-of-Inclusion methods, is not foundationally valid…and objective analysis of complex DNA mixtures with probabilistic genotyping software is promising, but has not yet been sufficiently and appropriately validated and their limitations to be considered reliable for all complex mixtures.”

The PCAST report also addressed the need for empirical standards in pattern-based forensic science methods, such as bite mark analysis, fingerprint matching, firearm/ballistic matching and shoe tread analysis: “In the case of bite-mark evidence, the report is especially critical. ‘PCAST finds that bitemark analysis does not meet the scientific standards for foundational validity, and is far from meeting such standards,’ it reads. ‘To the contrary, available scientific evidence strongly suggests that examiners cannot consistently agree on whether an injury is a human bitemark and cannot identify the source of [a] bitemark with reasonable accuracy.’

Related: Los Angeles Times, NDAA Letter opposing PCAST Forensic Science Report

About csidds

Dr. Michael Bowers is a long time forensic consultant in the US and international court systems.
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2 Responses to PCAST in the news – The DNA Blog from the New York Legal Aid Soc

  1. dnadmin says:

    Is it known to whom exactly this draft PCAST report has been shown to? I’m curious whether the NDAA for example has taken a critical look at it and considered the context. I see the IAI issued a statement on the report as well. Are organizations by any chance making comments based on news reports? THE CFSO has wisely chosen to digest and analyze the report prior to making any comment. I don’t understand the shock and awe response to the report. It seems the issues raised have been seriously talked about at least since the 2009 NAS report, but of course I haven’t read the PCAST report.

  2. csidds says:

    The PCAST draft was leaked and read by some at least. NDAA would have been better to hang fire like the CFSO. You are right about it being a reboot of the 2099 NAS. If you want a copy of the draft, send me an email.

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