Whether there were “reasonable grounds to suspect” the
commission of an offence can be controversial. Recently our Court of Appeal has
divided over whether there were reasonable grounds to suspect that the
defendant had possession of an offensive weapon. The case is not yet publicly
available, but suppression orders have lapsed. For people who have access to
the databases the neutral citation is [2017] NZCA 108. When it is available it
should be obtainable at nzlii.org
(as number 108 in the list).
Reasonable grounds to suspect that a weapon will be
found are required by s
27 of the Search and Surveillance Act 2012. Relevant matters were that it was
3 am when the defendant was questioned on a street and his response was “very
cagey” as to where he had come from and why he was in the street and not
wearing shoes although it was cold, his clothing (shorts and a camouflage
jacket) was similar to that of a person who was believed to be involved in
stealing from cars, he kept his hand in his jacket pocket and was behaving in
an agitated manner (at [17]). These circumstances where held to have given the
officer reasonable grounds to suspect that the defendant was in possession of
an offensive weapon. Peters J (who delivered the Court’s judgment) recorded her
dissent on this point. She did not consider that the circumstances relating to
the initial dispatch to the scene suggested violence or a person with a weapon,
and although the defendant was agitated nervousness is insufficient, and the
defendant had simply kept his hand in his pocket. Further, he had identified
himself, and there was nothing to suggest that he was going to use violence,
particularly as four constables were present at the time of the search (at
[26]).
The difference between the judges may be due to what
assumption was be made at the beginning of the analysis. Should the defendant
be assumed to have the probability of carrying a weapon that a randomly chosen
person would have, or a randomly chosen person of the defendant’s age, and
gender (to mention the two morally acceptable groupings), at that time of
night? To avoid exaggerating individual facts which will be considered later in
the analysis, the most neutral starting point should be chosen: the probability
that a randomly chosen person has possession of a weapon.
However, another starting point sounds as if it is
fair, but it will often lead to the opposite conclusion. This is that the
defendant is just as likely to have a weapon as not to have a weapon. The even
balancing here sounds neutral, until one asks, why should the defendant be
assumed to have a probability of 0.5 of having a weapon? It may be that only 2
people out of every 100 have possession of weapons, so why not start with a
probability for this defendant of 0.02?
Having chosen a starting point, the particular
circumstances are examined. The judges may well have agreed on the probative
value of each item and on the effect of taking them all into account together.
Suppose that they agreed that the occurrence of these combined circumstances was 14 times
more likely if the defendant had possession of an offensive weapon than if he did not. A judge who started with an assumption that the defendant was no
more likely to have a weapon than would a randomly chosen person, would
conclude that the ultimate probability that he had a weapon was around 0.3.
This could not be reasonable grounds to suspect. But a judge who started with
the assumption that the defendant was just as likely to have a weapon as not to
have one, would conclude that the ultimate probability that he had one was over
0.9. This would certainly be equivalent to reasonable grounds to suspect possession
of a weapon.
This analysis, which uses Bayes’ Theorem (something I
didn’t mention so as not to put off many readers), shows how important the
initial assumption is. A judge who started with the 0.5/0.5 assumption (giving
Bayesian priors of 1) would think that was a fair starting point, but was it?
The judgment does not mention whether any offensive
weapon was found in the defendant’s possession; other specified incriminating
things were found, in respect of which he was charged.
