stages. In Stage 1 there must be some evidence of the defence before the court
to support the defence. Often this evidence will come from the accused but it
may possibly come in whole or in part from the prosecution’s case. Stage 2
commences once this happens. There the prosecutor must rebut the defence
according to the ordinary criminal standard, namely proof beyond reasonable
doubt.
Against this background it is possible to explain the expression “air of reality”.
It
applies in Stage 1 to modify the common law rule just described. It is not
enough for the defence to produce or point to a prima facie case. They must
also be able to persuade the court that the defence has some probative force,
namely it has an “air of reality”. This is not a high standard but is something
more than a mere prima facie case. Logically this seems to mean that there is
some evidence that creates more than trivial plausibility that the defence is true.
A possible reason for introducing the “air of reality” requirement is that it helps
to overcome a problem that the prosecution can face with a defence, namely
to prove a negative. It has to prove the absence or non happening of the facts
that make up the defence, which can be difficult. The “air of reality”
requirement may alleviate this problem.
Measurement of Proof
Introduction
Step 3
involves
measurement. To measure whether the plaintiff or prosecution
has met the required standard of proof a court has to perform three tasks:
(1)
Phase 1: Actual Probability. The court has to ascertain the figure
indicating the probability that the party has made out their case (P%).
(2)
Phase 2: Required Probability. The court has to ascertain the figure
indicating the standard of proof that the party has to meet (X%).
(3)
Phase 3: Comparing the Probabilities. The court has to compare the two
probabilities to see if P is equal to, or greater than, X.
Phase 1. Actual Probability
Phase 1 is for the court to ascertain the figure indicating the probability that the
party has made out their case. We call this P%.
A court already has this figure because it found it in the preceding two steps of
the fact finding process. To understand how this was done let us retrace these
two stages:
(1)
In Step 1 the court has heard the evidence in a cause of action and thus
seen the versions of the truth.
(2)
In Step 2 the court has worked out the probability of truth, that is, the
probability (or degree of certainty) to which the plaintiff or prosecution has
made out its case. This, as we have said, is called P%.
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