THC detection is not the same thing as impairment
Why time since intake, THC detection and impairment are three different things.
A drug test can detect THC in your body. That does not tell you how impaired you are, if at all.
Time since intake, THC detection and impairment are three different things. They are related, but they are not interchangeable.
Detection and impairment are different
THC may remain detectable after its noticeable effects have reduced. How long it stays detectable varies between people, and depends on things like the product, the dose, how it is taken and how often.
Roadside oral-fluid devices are screening tools. They look for the presence of a substance rather than measuring how a person is driving.
A positive roadside test can still have legal consequences, depending on where you are and the law that applies there.
What the New Zealand evidence review found
The New Zealand Independent Expert Panel on Drug Driving reviewed the science on cannabis, driving impairment, blood THC concentrations and oral-fluid testing.
For inhaled cannabis, the Panel reported that the strongest effects generally occur soon after use, and that most acute effects commonly subside within around three to four hours. Effects vary considerably between individuals.
The Panel also found that blood THC concentrations correlate poorly with the effects of the drug, and that oral-fluid THC concentrations cannot reliably predict blood THC concentrations.
What DriveClear does and does not do
DriveClear records what you tell it: the intake, and the time that has passed since it.
- It does not determine whether you are safe or fit to drive.
- It does not predict whether you will pass or fail a roadside drug test.
- It does not provide a legal THC clearance time.
A Personal Reference Period is your own conservative record-keeping reference period. Completing one does not mean effects have ended, that THC is no longer detectable, or that drug-driving requirements no longer apply.
DriveClear is a personal record-keeping tool. It does not replace applicable law, medical advice, roadside testing or decisions made by authorities.
Source
Independent Expert Panel on Drug Driving. Final Report: Recommending Statutory Limits for Drug Concentrations Relating to Impaired Driving. April 2021.
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