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Private Bag 6995
Wellington 6141
New Zealand
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www.nzta.govt.nz
9 July 2026
Nigel Gray
[FYI request #34901 email]
REF: OIA-22561
Dear Nigel
Request made under the Official Information Act 1982
Thank you for your email
of 16 June 2026 requesting the fol owing information regarding drug-related
crashes, for the period from 1 January 2014 to the present, under the Official Information Act 1982
(the Act):
2.1 Definitions and classification rules Please provide all NZTA definitions of:
“drug‑
related crash”
“drug‑
impaired driver”
“drug involvement”
For each definition, please provide:
the date it was adopted
the reason for adoption
any changes over the last 10 years
the scientific, legal, or policy basis for the definition
NZ Transport Agency Waka Kotahi (NZTA) does not use the term
drugs-related. Instead, NZTA staff
use the terms
“drugs proven”,
drugs involved” and “drugs suspected.
The
Drugs proven Code 109 is applied when:
• a blood test result for drugs is positive and the coder believes that, where there is a positive test
for drugs, the positive results is not solely because pharmaceutical drugs have been
administered by an emergency responder after the crash, but before the administration of a
drug test; or
• an oral fluid confirmatory test is positive.
For
Drugs suspected, Code 108 is applied against a driver in the fol owing circumstances:
• the driver refused a test for drugs; or
• the New Zealand Police officer attending the crash had good cause to suspect that the driver
has been taking drugs; or
• the driver was arrested pursuant to section 120 of the Land Transport Act 1998; or
• there were two positive oral fluid screening tests, and the result of a blood test is not available.
New Zealand Police provides crash data to NZTA. Our Customer Operations Support team then
analyses the data for each crash and determines which factors likely caused or contributed to the
outcome of a crash. A code is applied to each of these factors, and further information on these is
available on our website at https://www.nzta.govt.nz/assets/Safety/docs/cas-factor-codes.pdf
The al ocation of these codes is often a matter of judgement. The coder must interpret the narrative of
the attending New Zealand Police officer along with any other data provided.
A crash may (and often has) more than one contributing factor, but a crash does not have a primary
cause attributed to it. When crashes are reported, contributing factors are sometimes grouped into
road safety categories and, because a crash can involve multiple factors, it can be counted in more
than one category.
2.2 Evidential thresholds
Please provide the evidential thresholds NZTA uses to classify a crash as drug‑
related,
including:
presence of a substance
impairment
contribution
causation
For each threshold, please provide:
how it is determined
who determines it
whether Police evidence is required
whether coronial findings are required
whether toxicology presence alone is sufficient
When coding crashes, NZTA does not use the term
drugs-related but staff can explain what triggers
the coding of
drugs proven.
Please refer to our response for part 2.1 of your request, and Attachment 11 which was provided for
part 3 of our response to your previous request (reference OIA-22302).
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2.3 Classification workflow
Police have stated they do not classify crashes and hold no workflow for doing so.
Accordingly, please provide NZTA’s workflow for assigning the “drug‑
related” label,
including:
the staff, units, or contractors responsible
the decision‑
making process
any internal guidance or SOPs
any automated or algorithmic processes
any quality‑
assurance or review steps
If no workflow exists, please confirm this explicitly.
NZTA does not use a workflow for
drugs-related but do for
drugs proven and
drugs involved.
Please also refer to our response to part 2.1 of your request.
2.4 Source data and authority
Police have stated they:
do not determine impairment
do not determine causation
do not classify crashes
do not define “drug‑
related crash”
do not audit accuracy
Given this, please provide:
the source data NZTA relies on to assign the “drug‑
related” label
whether NZTA receives coronial toxicology
whether NZTA receives coronial causation findings
whether NZTA uses Police TCR fields that Police themselves state are not causal
determinations
NZTA does not official y use the term
drug-related when providing coding for crashes. Please refer to
our response for part 2.1 regarding
Drugs proven Code 109 and
Drugs suspected Code 108.
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We can, however, further advise that code 221
Impaired non-driver (pedestrian / cyclist / passenger,
etc) is used when drugs were present in non-driving parties such as passengers, cyclists or
pedestrians who may have contributed to the crash.
In rare cases where drugs may have contributed to the cause or outcome of a crash, but where none
of the above-mentioned factors are applicable, Code 220
Other drugs may be applied against a
person involved in the crash.
As noted in our response for parts 2.1, 2.2 and 2.3,
drug-related is not a term used by NZTA for
contributing factors in a crash.
For fatal crashes, NZTA receives serious crash unit reports and coroner’s reports. Coders read these
reports and revise the coding of these crashes when considered necessary.
2.5 Reconciliation of the contradiction
Police have stated:
“Police does not hold internal documents reconciling this distinction.”
Accordingly, please provide NZTA’s reconciliation of the fol owing contradiction:
NZTA publishes statistics claiming specific causal categories (e.g., “drug‑
related”), while
Police state no single factor can be confidently identified as the primary cause of a crash.
Please provide:
all internal documents, emails, memos, or guidance addressing this contradiction
any risk assessments relating to misclassification
any limitations statements used internally or externally
NZTA’s position on this matter is that no single factor can be confidently identified as the primary
cause of a crash, which reflects the reality that crashes typically involve multiple contributing factors.
These can include driver behaviour, vehicle condition, road environment, and external conditions – all
of which often interact in complex ways.
For reporting and analysis purposes, while crash categories are based on identified contributing
factors, this does not mean that a single factor is treated as the sole cause. Instead, it indicates that
the factor was present and contributed to the crash. This means that a single crash may be included in
more than one category where multiple contributing factors are identified.
As a result, there is no inconsistency to reconcile. The statement reflects how crashes occur in
practice, while the use of categories is simply a way to analyse and report on contributing factors to
support road safety interventions and monitoring of trends in high-risk behaviours. I am therefore
refusing your request for
all internal documents, emails, memos, or guidance addressing this matter
under section 18(e) of the Act as the documents alleged to contain the information requested do not
exist.
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We can, however, advise that there is a reference to
Drug-related deaths and serious injuries (SAFE7)
in our
Statement of Performance Expectations, which is available on our website. As an example, you
should refer to page 29 of the 2025-26 report which can be found at:
www.nzta.govt.nz/assets/resources/statement-of-performance-expectations/2025-2026/spe-2025-
2026.pdf
This measure includes both alcohol and drugs as contributing factors. The definition of SAFE7 from
our
Statement of Performance Expectations’ 2025-26 explanatory notes states that it counts the
number of road deaths and serious injuries where a driver has tested positive for alcohol or drugs with
data from the Crash Analysis System (CAS). This information is available on our website at:
www.nzta.govt.nz/assets/resources/statement-of-performance-expectations/2025-2026/spe-2025-
2026-performance-measure-explanatory-notes.pdf
NZTA also reports the separate components in page 11 of the quarterly report for the breakdown.
2.6 Accuracy, audits, and validation
Please provide:
any audits, reviews, or assessments of the accuracy of NZTA’s “drug‑
related crash”
classifications
any documents discussing limitations, uncertainties, or risks associated with assigning
causal labels
any correspondence with Police or the Ministry of Transport regarding classification
accuracy
If no audits exist, please confirm this explicitly.
We last undertook a review of codes for contributing factors in crashes at the end of 2015. Since then,
no further review of codes has been done. We tried to locate the 2015 review, which included
actioning a digital sweep of our internal document storage system but, due to the length of time (nearly
11 years), we were unable to find a copy of it. I am therefore refusing this part of your request under
section 18(e) of the Act as the document al eged to contain the information, despite reasonable efforts
to locate it, cannot be found.
Other documents requested have also been provided as Attachments 1 and 2 for part 5 of our
response to OIA-22302 2026.
Under section 28 of the Act, you have the right to ask the Ombudsman to review my decision to refuse
part of this request. The contact details for the Ombudsman can be located at
www.ombudsman.parliament.nz.
In line with NZTA policy, this response will soon be published on our website, with personal
information removed.
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If you would like to discuss this reply with NZTA, please contact Ministerial Services by email to
[NZTA request email].
Yours sincerely
Josh Driscoll
Manager, Ministerial Services
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