The US DOJ published a statement on the Sept. 2016 President’s Council of Advisors on Science and Technology (PCAST) Report, Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods. The DOJ explains its disagreements with the 2016 report in the statement.
In summary, the DOJ’s position is that:
- Traditional forensic pattern examination methods—as currently practiced—do not belong to the scientific discipline of metrology. Forensic examiners visually compare the individual features observed in two examined samples, they do not measure. The result of this comparison is a conclusion that is stated in words (nominal terms), not magnitudes (measurements).
- PCAST’s claim that forensic pattern examination methods can only be validated using its non-severable set of nine experimental design criteria is inconsistent with its own examples, international laboratory standards, and authorities in experimental design. There is no single scientifically recognized means by which to validate a scientific method.
- Casework error rates cannot be established through the exclusive and non-severable application of PCAST’s experimental design criteria. No single error rate is applicable to all labs, examiners, or cases.
The Innocence Project called on the DOJ to retract its statement on the widely-accepted PCAST Report. Their Feb. 4, 2021 letter is available here. Here is a response to the DOJ statement by Maneka Sinha in Slate.