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To: Official Information Act Team, NZ Transport Agency Waka Kotahi
From: Nigel Gray
Subject: Request for information — Classification of “drug‑related” crashes

Dear New Zealand Transport Agency
1. Purpose of this request
This request follows a recent OIA response from New Zealand Police (IR‑01‑26‑18611, 12 June 2026), in which Police confirmed:

they do not classify crashes as drug‑related

they do not hold definitions of “drug‑related crash”

they do not apply thresholds, criteria, or decision rules

they do not determine impairment or causation

they do not reconcile the contradiction between “no single cause” and the use of causal labels

they do not audit the accuracy of any such classifications

Police further stated that NZTA is responsible for any classification used in national reporting.

Accordingly, this request seeks the classification logic, definitions, and evidential basis NZTA uses when publishing “drug‑related crash” statistics.

2. Request
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

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

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.

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

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 following 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

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.

3. Time period
Unless otherwise stated, this request covers the period 1 January 2014 – present.

4. Format
Please provide all documents in searchable electronic form (PDF, DOCX, XLSX, or equivalent).

5. Right to complain
I note my right to complain to the Ombudsman if this request is refused or delayed.

Yours faithfully,

Nigel Gray