Anyone thinking of voting ‘yes' to legalising recreational marijuana should look at the data.

For starters, the black market continues to thrive where the drug is legal. Statistics Canada reported last year that still only 29 per cent of users buy all of their product from a legal source.

People will still want to buy cheaper, higher potency products under the table or from gangs.

In Colorado, in the four years post-legalisation, organised crime sky-rocketed.

Take something as simple as road safety: a 2018 Colorado study found 69 per cent of cannabis users had driven stoned in the past year; 27 per cent said they drove high almost daily.

And what of the impact on young people? According to virtually every scientific review, marijuana use during adolescence is linked with poorer mental health and lower scholastic achievement.

Under the law we'll be voting on in September, the daily use allowance would be 14g. This may sound like ‘a small amount' but according to the NZ Herald it's enough for 14-42 joints.

How do we fight to reduce suicide rates among young people, but at the same time tell them it's totally fine to smoke a drug known to increase the risks of psychosis, anxiety, suicide and depression, etc?

How hypocritical is it to promote ‘Smokefree 2025', while saying smoking dope is fine?

As for the claims of tax revenue bringing benefits to the community, drug supporters over-estimate the revenue and underestimate the massive costs to society.

S Paterson, Omanu