Abstract
How should forensic scientists and other expert witnesses present their evidence
in court? What kinds and quality of data can experts properly draw on in
formulating their conclusions? In an important recent decision in R. v T1 the Court
of Appeal revisited these perennial questions, with the complicating twist that the
evidence in question incorporated quantified probabilities, not all of which were
based on statistical data. Recalling the sceptical tenor of previous judgments
addressing the role of probability in the evaluation of scientific evidence,2 the
Court of Appeal in R. v T condemned the expert’s methodology and served notice
that it should not be repeated in future, a ruling which rapidly reverberated around
the forensic science community causing consternation, and even dismay, amongst
many seasoned practitioners.3 At such moments of perceived crisis it is essential
to retain a sense of perspective.
There is, in fact, much to welcome in the Court of Appeal’s judgment in R. v
T, starting with the court’s commendable determination to subject the quality of
expert evidence adduced in criminal litigation to searching scrutiny. English courts
have not consistently risen to this challenge, sometimes accepting rather too easily
the validity of questionable scientific techniques.4 However, the Court of Appeal’s
reasoning in R. v T is not always easy to follow, and there are certain passages in
the judgment which, taken out of context, might even appear to confirm forensic
scientists’ worst fears. This article offers a constructive reading of R. v T, emphasising its positive features whilst rejecting interpretations which threaten,
despite the Court of Appeal’s best intentions, to diminish the integrity of scientific
evidence adduced in English criminal trials and distort its probative value.
Original language | English |
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Pages (from-to) | 347-356 |
Number of pages | 10 |
Journal | Criminal Law Review |
Volume | 5 |
Publication status | Published - 2011 |