Roadside Oral-Fluid Drug Testing – Presence Is Not Impairment POSITIVE TEST? MAKE THEM PROVE IMPAIRMENT.

Page 1Public Court Position – Roadside Drug Testing
PUBLIC COURT POSITION
Roadside Oral-Fluid Drug Testing – Presence Is Not Impairment
POSITIVE TEST? MAKE THEM PROVE IMPAIRMENT.
Core issue
The Crown may allege that a roadside oral-fluid test result justifies enforcement.
However, the Ministry responsible for transport policy has confirmed that a positive oral-fluid result
indicates recent drug use, and that recent use is only a proxy for impairment. The Ministry has also
confirmed that a positive result does not prove that a driver was unsafe, impaired, or causally
responsible for any road-safety risk.
That creates a serious evidential and public-law issue.
The public has been told this regime is about impaired or unsafe driving. But the Ministry response
confirms that the test does not prove either.
Court position
This position does not say that road safety is unimportant. Road safety plainly matters. The issue is
whether an enforcement consequence can be treated as if impairment has been proven when the
responsible Ministry accepts that the test is only a proxy.
A proxy is not proof. A policy assumption is not evidence. Presence or
recent use is not, by itself, proof of unsafe driving.
Points to put before the Court
1. The result is not proof of impairment
– The defendant does not accept that a positive oral-fluid result proves actual impairment.
– The Ministry has confirmed that recent use is only a proxy. A proxy is not proof. A proxy is an
assumption.
– Unless the Crown can prove actual impairment by admissible evidence, the Court should not treat a
positive oral-fluid result as proof that the defendant was unsafe, impaired, or causally responsible for
any risk.
2. The Crown must prove lawful testing and proper process
– The lawful basis for stopping or testing the driver;
– The statutory power relied on;
– The identity, approval status, calibration, maintenance, and reliability records for the testing device;
– Officer training and compliance records;
– Chain of custody and laboratory confirmation records, if relied upon;
– The exact drug or substance alleged, and the threshold or concentration relied upon;
Page 2Public Court Position – Roadside Drug Testing
– Whether the alleged substance could arise from lawful medication;
– Whether the defendant was given all statutory rights, options, and challenge mechanisms.
3. The Crown must identify what is actually alleged
– The Crown should clarify whether it alleges actual impairment, unsafe driving, recent use only,
presence only, concentration above a statutory threshold, refusal or failure to comply, or some other
statutory offence.
– If actual impairment is not alleged, then the Crown and enforcement agency should not represent the
matter as proof of impaired driving.
4. Public-harm analysis does not exist
– The Ministry has confirmed that no financial analysis of public harm, and no revenue or Crown financial
benefit analysis, exists for the enforcement framework.
– That matters because enforcement can cause fines, demerit points, licence loss, employment loss,
business loss, insurance consequences, court debt, family hardship, and reputational harm.
– The Court should be slow to accept broad public-safety claims where the responsible Ministry has not
assessed the public financial harm caused by the enforcement framework itself.
5. The defence position
– Presence is not impairment.
– Recent use is not unsafe driving.
– A proxy is not proof.
– Policy is not evidence.
– An enforcement assumption is not a proven fact.
Disclosure sought
The defendant seeks disclosure of all records relied upon, including scientific validation, device
reliability, officer compliance, chain of custody, laboratory confirmation, statutory authority, and any
records said to justify treating recent use or presence as sufficient for enforcement.
Until those records are produced and tested, the defendant does not accept that the Crown
has proved actual impairment, unsafe driving, or causal road-safety risk.
PRESENCE IS NOT IMPAIRMENT.
RECENT USE IS NOT UNSAFE DRIVING.
A PROXY IS NOT PROOF.
Source note
Based on Ministry for Cities, Environment, Regions and Transport OIA response OC260507, dated 3 July 2026, addressed to
Tracy Lynch. The Ministry stated that recent drug use is a proxy for impairment and does not prove that a driver was unsafe,
impaired, or causally responsible for any road-safety risk. The Ministry also stated that no financial analysis of public harm or
revenue/Crown financial benefit analysis exists for the relevant enforcement framework.
Public information prepared for discussion and court-readiness. This is not legal advice. Anyone facing enforcement should
obtain legal advice about their own case, charge, deadline, and available statutory challenge process.
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