Lies, Damned Lies, and Conviction: The Misuse and Misunderstanding of Statistical Evidence in R v Clark
It is now well established that bad lawyering, bad expert evidence and bad police work can contribute to wrongful convictions but do innocent people spend time in prison owing to bad math? Photo: Diacritica (Wikipedia)
Author: Claire Horsnell, Osgoode Hall Law Student
The truism, originally attributed to nineteenth-century British prime minister Benjamin Disraeli and popularized by Mark Twain, about there being three kinds of lies—“lies, damned lies, and statistics”—nods ironically toward the ways in which statistics can be manipulated to support a speaker’s point. However, for non-statisticians, the use of impressive-sounding numbers to support a contention can be very convincing; numbers, of course, are a fundamentally reliable way to quantify and understand the world around us. However, an error in calculation or misunderstanding—or worse, a deliberate misrepresentation of statistical evidence—in a courtroom can have dire consequences.
Probably the most notorious instance in which statistics played a part in a wrongful conviction is the British case of Sally Clark. Clark, a solicitor based in Manchester in the north of England, was not only a victim of an egregious miscarriage of justice, but also of tragic circumstances. Her first son, Christopher, was born healthy but passed away at the age of two-and-a-half months, after falling unconscious in the family home. Clark’s second son, Harry, was born two years later—and died at the age of eight weeks, after he was found unconscious, and attempts to resuscitate him failed.
Clark and her husband were arrested shortly afterward; the charges against Steve Clark were dropped, but Sally Clark faced two counts of murder. She denied the charges.
The most controversial element of Clark’s trial was the testimony by then eminent paediatrician Professor Sir Roy Meadow. Meadow testified on the stand that the chances of [...]