Why it matters in the Letby case
Post-conviction commentary argues the Cannings principle is engaged by the post-conviction expert dispute in the Letby case.
Legal explainer
The Cannings principle
In R v Cannings (2003) the Court of Appeal observed that where serious disagreement exists between reputable experts on the medical cause of a death, prosecutions should not proceed on the disputed expert evidence alone.
Legal explanation1Court/official
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Prosecution position
The Crown's case rested on expert evidence about the mechanism of each death or collapse, presented at trial as sufficiently settled to support conviction.
Expert challenge / post-conviction reading
Post-conviction commentary argues the Cannings principle is now engaged: in R v Cannings (2003) the Court of Appeal observed that where serious disagreement exists between reputable experts on the medical cause of a death, a prosecution should not proceed on the disputed expert evidence alone.
What remains uncertain
Cannings speaks to whether a prosecution should proceed, and this conviction has already been returned. How the principle bears on a completed trial rather than a prospective prosecution is a question for the Court.
Common questions
What is the Cannings principle?
The observation in R v Cannings (2003) that where reputable experts seriously disagree about the medical cause of a death, a prosecution should not proceed on that disputed expert evidence alone.
Is there serious expert disagreement in this case?
The post-conviction record contains a fourteen-member international panel finding no medical evidence of deliberate harm in the cases reviewed, against the Crown's trial experts. Whether that meets the Cannings description is the argument being made.
Does Cannings apply after conviction?
It was framed as guidance about whether to prosecute. Its application to a completed trial is part of what a court would have to decide.
Who was Angela Cannings?
A mother convicted in 2002 of murdering two of her sons; the Court of Appeal quashed the conviction in 2003. See the linked comparative analysis.
Related reading
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