Chapter 24
Probability of Truth: Overall Facts
Introduction
One Version
Several Versions
[W]e fear that out of any 12 citizens [on a jury], there’s a good chance one
will have a screw loose. Real experience tells a different story. Fewer than
10% of juries deadlock, most splitting 6-6 or 7-5. Fewer than 1 per cent split
11-1. And of those, how do we know who’s a “rogue” juror and who’s
Henry Fonda in “12 Angry Men,” the lone hold-out who got it right?
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Introduction
Step 2 Probability of Truth: Stage 2
Nature of Step 2
This chapter discusses Stage 2 in Step 2 of the model for proving facts. Step
2 of the model for proving facts assesses the probability that each party’s case
is true. Typically, a party’s overall case is founded on specific facts based on
different types of evidence and evidence from different witnesses. This means
that the probability of truth for each specific piece of evidence may be
different. Stage 1 of Step 2, discussed in the preceding chapter, explained how
a court can assess the probability of truth for these specific pieces of
evidence. Here in Stage 2 of Step 2 in this chapter we see how a court uses
these specific probabilities to determine the probability that the overall version
of the facts that makes up a party’s case is true.
Stage 2 of Step 2 uses one form of reasoning, namely the rules of
probability.
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These involve mathematical calculations that to some extent
allow us to derive one probability when we know another. An illustration is the
complementarity rule, which was explained earlier.
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Thus in Stage 2 the court
takes the probabilities that specific facts are true (which was determined in
Stage 1) then uses these probabilities to calculate the probability that the
overall version of the facts is true.
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Malcolm Knox “The case for the lone voice of dissent” The Sydney Morning
Herald 11 November 2005. The comment was made in discussion of a proposal by the
New South Wales Government to introduce majority jury verdicts.
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For an explanation and illustration of these rules see Christopher Enright (2009)
Legal Reasoning Chapter 9 Probability
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Chapter 21 Model for Proving Facts
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