From Schedule 5 of the legislation:

• 3 ng/ml is the “high-risk blood concentration level” for THC.
• 1 ng/ml is the “tolerance blood concentration level” for THC.

What is the difference?

Medsafe says:

Schedule 5 has two blood concentration levels for each listed qualifying drug: tolerance and high-risk.

Exceeding the lower level (tolerance) is an infringement and could result in a fine or licence demerit points.

Exceeding the higher level (high-risk) could result in a criminal charge and the driver may be disqualified from driving or sentenced to prison.

To get an idea of what other countries are doing see https://www.ncids.org/2021/marijuana-impairment-faq/

How long can THC be detected in the blood after ingestion of marijuana?

“Low THC levels of a few nanograms per milliliter (ng/ml) in blood can result from relatively recent use (e.g., smoking within 1 – 3 hours) when some slight or even moderate impairment is likely to be present, or it can result from chronic use where no recent ingestion has occurred and no impairment is present.” - Compton at p. 7.

Don’t get me wrong. I don’t want to be on the road with a bunch of stoned people but it seems pretty bleak to me. A medical user could definitely hit 1ng/ml without being impaired.

There is another RNZ story on this from 11 Oct.

I really like:

Okay kids, we’re going to take a nap and then when we wake up we’re going to clean the house!

They nap for ages…