Every year, New Zealand’s courts determine well over
200,000 criminal, civil, family, youth and other
legal matters. These decisions affect people’s
liberty, livelihoods, businesses, finances, reputations and
families. Yet despite the enormous responsibility entrusted
to the judiciary, New Zealand has no official measure of how
often court decisions are later found to contain significant
legal or factual errors.
Unlike many areas of public
administration, where performance indicators are routinely
collected and published, there is currently no single
national dataset recording:
- how many judicial
decisions are appealed; - how many appeals succeed
because of material legal or factual error; - how many
convictions are later overturned after fresh evidence
emerges; - the financial cost of correcting judicial
errors; and - the wider human cost of miscarriages of
justice.
Without this information, policymakers,
legal professionals and the public cannot accurately assess
whether the justice system is performing as effectively as
it could.
New Zealand has experienced several of the
country’s most significant miscarriages of justice,
including the cases of Arthur Allan Thomas,
David Bain, Teina Pora,
Rex Haig, and Alan
Hall.
Mr Hall spent almost 18 years in prison
before the Supreme Court quashed his convictions in 2022 and
entered verdicts of acquittal. He later received almost
$5 million in compensation, and New Zealand
Police formally apologised for shortcomings in the original
investigation.
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These cases demonstrate that serious
failures can occur within the criminal justice system. They
also illustrate that miscarriages of justice are often the
product of multiple factors, including police
investigations, forensic evidence, prosecutorial decisions
and judicial rulings. They should not be interpreted as
establishing that judges alone were responsible for the
outcomes.
In the United Kingdom, 736 sub-postmasters
were wrongly prosecuted by the Post Office between 1999 and
2015 in cases linked to the faulty Horizon IT system. More
than 700 people were wrongly convicted, making it the
largest miscarriage of justice in British legal
history.
- In addition, around 3,500
sub-postmasters experienced financial losses, demands to
repay nonexistent shortfalls, contract terminations, or
other serious consequences, even though they were not all
criminally prosecuted. - The Horizon IT scandal has
become one of the world’s leading examples of how systemic
failures—involving technology, disclosure obligations,
investigative practices, and judicial processes—can
combine to produce a large-scale miscarriage of justice,
with the Court too readily accepting evidence that was later
shown to be unreliable, incomplete, and
wrong..
Measuring What We Can
Although
New Zealand has no official judicial error rate, it is
possible to estimate a minimum identified error rate by
analysing court statistics, appeal outcomes and Criminal
Cases Review Commission referrals.
For example, New
Zealand’s courts determine approximately 220,000 matters
each year, then:
- If 0.1% of decisions were later
found to contain a significant reversible error, this would
represent approximately 220 cases annually. - If 0.5%
of decisions required correction, this would amount to
approximately 1,100 cases annually. - If 1% of
decisions were ultimately found to be materially incorrect,
approximately 2,200 New Zealanders each year would be
affected.
These figures are illustrative only.
They are not estimates of New Zealand’s actual judicial
error rate. They simply demonstrate that even a very small
proportion of incorrect decisions could have significant
human and financial consequences when applied across the
volume of cases decided each year.
Equally important
is recognising that these calculations would still
understate the true picture. Many incorrect decisions are
never appealed because litigants cannot afford legal
representation, legal aid is unavailable, settlements occur
before appeal, or new evidence never emerges. Likewise, a
successful appeal does not necessarily mean the original
judge acted incompetently or improperly; appellate courts
exist because reasonable judges can differ on difficult
legal questions and because evidence or legal
interpretations may later change.
A National Judicial
Performance Study
A comprehensive independent study
could answer important questions that remain unknown
today:
- How many court decisions are appealed each
year? - What proportion of appeals result in judgments
being overturned or materially varied? - Which
jurisdictions experience the highest rates of successful
appeal? - How long does it take to correct significant
judicial errors? - What is the financial cost of
appeals, retrials, compensation payments and related
proceedings? - What systemic improvements could reduce
the likelihood of future miscarriages of
justice?
Such research should not be viewed as a
criticism of judicial independence. On the contrary,
judicial independence is strengthened when accompanied by
transparent evaluation, continuous learning and
evidence-based reform.
Public confidence in the
justice system depends not only on fair decision-making, but
also on the willingness of institutions to examine their own
performance honestly.
Reliable information is the
foundation of informed public debate.
The first step
toward reducing miscarriages of justice is understanding how
often they occur, why they occur, and what lessons can be
learned to better protect all New
Zealanders.
