It's not exactly news that our criminal prohibition on possessing marijuana is a really bad policy. But a bunch of news stories this week serve to remind us just how bad it is.

One of the great things about my local paper, the Otago Daily Times, is that it still prints daily reports of all the trials that take place in each of the region's various local courts. For an insight into the manifold frailties and foibles of humanity, as well as a lot of sadness and the occasional spot of humour, it is hard to beat. I read it every day.

Friday's edition, however, really irritated me. It contained an account of two cases involving individuals caught growing small amounts of marijuana in their own homes for their own personal use. The first was a man in his 40s whom, the case account intimated, is suffering from a serious medical condition for which cannabis is a palliative treatment. Nevertheless, due to the fact that he had previous drug cultivation convictions (and due to his possession of an unlicensed firearm for reasons entirely unrelated to the drugs), he was sentenced to a period of community detention - meaning that the taxpayer will be paying people to check up him for weeks to come to make sure he stays at his home and so doesn't ... what, smoke cannabis in his home for pain relief?

The second was a man in his 70s, who had used cannabis for many years because he liked doing so. As this was the first time he had appeared in court, he was discharged without conviction - but only after paying $1000 to charity and facing the inconvenience, cost and stress of having his home searched by the police, charges laid in court and waiting on what sentence the judge would decide to apply to him. Plus, as his case worked through the system, he missed traveling overseas to witness a relative's graduation ceremony - a memory lost to the family as a whole.

What irritated me about these reported cases is that they are just so unnecessary. Because they came in the same week as media reported on a Treasury think-piece, uncovered and released by the same Nelson lawyer, Sue Grey, who worked out that personally importing medical cannabis is lawful. This think piece suggested that not only does keeping marijuana illegal directly impose hundreds-of-millions of dollars in enforcement costs, it also deprives the Government of some $150 million in potential excise revenue (or, to put that number in perspective, some three Housing NZ dividends a year). And it also fosters an illegal market largely controlled by criminal groups, results in hundreds of people annually being labelled as "criminals" for just doing something that they enjoy, while having minimal apparent impact on the numbers of people who actually engage in the targeted activity.

Such a policy is, to co-opt Bill English's verdict on our general prison policies back in 2011, a "moral and fiscal failure". And as my ODT editorialised back then, "If the policies do not work, why would any government throw money hand over fist at them." Note the lack of a question mark at the end of that sentence. It is an entirely rhetorical statement.

So why is it that the Treasury report, described as a "conversation starter" by a spokesman, has been completely disavowed by its Minister, Bill English? How can this be the same Minister who sees the "moral and fiscal failure" of prisons, and who so emphasises the need for linking expenditure to results in an evidence-based way in other policy areas:

There are increasing signs in education that the system is starting to understand that there should be a link between resource and achievement. We have one of the more expensive compulsory education systems in the OECD yet achievement has, until recently, not moved for about 20 years. So if we’re spending more we should expect more in terms of achievement and if that linkage is not there, then what is it that we’re spending money on? We have indicated our willingness to spend on inputs that will lift achievement - such as the $362 million quality teaching package announced at the beginning of the year – which is a fairly big commitment to evidence-based policy.

Because note that this heralded $362 million - this "fairly big commitment to evidence-based policy" - is less than the amount the Treasury report said we spend on enforcing a prohibition on possessing marijuana which quite obviously is not working. So why on earth would any sane Government keep on throwing large chunks of money at it?

Over at the Dimpost, Danyl Mclauchlan suggests the policy inertia is because "[a]ny politician or government signing off on any kind of cannabis reform dooms themselves to be depicted as stoned pot-smoking hippies in every political cartoonist, pontificating talk-back host and lazy political editors’ sights yea unto the end of days." If that analysis is true - and I do urge you to note the source, so treat with all due skeptical care - then this is where we are left.

We're spending millions and millions to drag 40-something sick people, 70-something social smokers and many, many more besides through our courts and punishing them as criminals (after spending countless police hours raiding their homes and processing their arrests) for no good reason whatsoever, but we can't stop doing so because (most of) our MPs (with a few honourable exceptions) are scared of being ridiculed for doing the sensible thing.