If one was to pick a politician most likely to trigger a debate about whether cannabis should be decriminalised, not many people would have had Don Brash at the top of their list. That it is Dr Brash who has labelled the current approach a failure should make it harder for National and Labour to ignore this issue.

Let us look at what Dr Brash actually said:

Laws that do not serve that purpose, and indeed possibly make us more vulnerable to criminals, should not be on the statute books to begin with.



In that respect I have to say, after long and painstaking reflection, I have come to have serious questions about our current marijuana laws.



Since 1927, it's been a criminal offence to possess, use, produce or sell cannabis in New Zealand.



The police and the courts spend some $100 million of taxpayer money a year enforcing this prohibition of a drug believed by many people to be less dangerous than tobacco or alcohol. Is there really any point to this?



Some 6000 people are prosecuted every year for cannabis offences. Are we any safer for this?

I am not an advocate for legalising all drugs. But I do agree with Dr Brash that the current laws around cannabis have largely failed, and that at a minimum personal use and consumption should not be a criminal offence.

The opportunity cost of having so much police time spent on cannabis offences is a real issue, as Dr Brash says:

I'm haunted by the thought that all that police time and all those police resources could be better deployed in actually keeping us safe from real criminals intent on harming us, instead of making criminals of 400,000 New Zealanders who are harming no one – except, arguably, themselves, which is their prerogative in a free society.

The Law Commission has also advocated a mandatory cautioning scheme for anyone charged with a personal possession or use offence. For Class C drugs such as cannabis they recommend that a person only be prosecuted from their fourth offence. This could be a sensible compromise between full decriminalisation and the current law.

Do you think the current law is working well? Or do you support decriminalisation, or maybe the Law Commission's halfway house of a mandatory cautioning scheme for personal possession and use offences?

David Farrar is a centre-right blogger affiliated to the National Party.