Why the constitutional review panel is a bit like getting a few mates round at the weekend for some DIY

On Saturday night emergency services were called to Glen Eden, Auckland where a deck had collapsed dropping 30 people and a hot barbecue about a storey to the ground. The home's new owner said it looked as if the deck had simply been tacked on to the side of the house with no proper reinforcements. It put me in mind of the current constitutional review.

After months holding public meetings around the country, the review panel got a bit of publicity over the weekend. That must have been a relief for the panel, given their mandate is to spark discussion. As was utterly predictable they've made little progress on that front. Why? Because it takes a certain type to head off one evening to a community hall to hear about such issues. And it's a hard topic for the media to cover because most New Zealanders don't have the time or inclination to learn about our constitutional arrangements.

Indeed, from a distance it seems the panel's critics – from both sides – are generating as much debate as the panel itself, with their own public meetings.

None of that is meant as criticism of the panel, the members of which have done all they realistically can. And neither do I think the panel a waste of time, because you have to start somewhere and any conversation is another step along the road.

But the truth is that, like a fire extinguisher, people only care about a constitution in an emergency. We're all happy to let it gather dust in the meantime. For all the fine talk, we're not going to generate a grass roots discussion without some sort of spark.

The deck collapse reminded me of our constitution, because like that DIY construction, it's just tacked onto our national life. And the panel is just a group of guys whacking in a few nails or slapping on some paint. They don't have the tools or consent to do a serious overhaul.

Our constitution – a mish-mash of New Zealand and English laws and traditions – is not foundational in this country. Matthew Palmer has written about us "tinkering in the constitutional shed" and our constitution is, in a very New Zealand sense, a great bit of Kiwi DIY. Like that deck, it's an add-on that reflects New Zealand's 'she'll be right' attitude and has received little proper scrutiny.

And like that deck, if we load it with too much weight, it's likely to pull fall away from under our feet. New Zealanders find it hard to care about the constitution right now, because there's no jeopardy around it. But like Pike River or leaky homes or this deck, we will at some stage regret not doing more when we had the chance.

Because, conversely, the best time to sort out your constitution is when there is no emergency and calm heads can prevail. If we come to re-write our constitution in the midst of some crisis, our discussion and choices will be perverted by the specific.

Demographic changes are one of the most likely specific triggers for constitutional change. As our culture is changed by immigration we're likely to be confronted more often by challenges to some of the basic principles that our constitution espouses.

I'm sure the Maori Party is aware of that and it's one of the reasons it's pushing for more constitutional conversation. The review panel is, after all, the result of a coalition agreement between it and National. It knows that since the Maori renaissance in the mid-70s, most of our cultural discussion has been through a bi-cultural lense. And quite rightly. But that won't last forever.

This week we've heard Pacific leaders raise the question of ethnicity-based seats on local authorities for their people. That's not a good idea, but it's a sign of other minorities seeing the gains for Maori in recent years and looking to mimic their successes. It's a sign that we are almost certain to move from a bi-cultural conversation to a multi-cultural one in the years ahead.

So if Maori want the Treaty of Waitangi entrenched in law, their window of opportunity is limited.

It's a slow journey at this point, however, because New Zealanders don't feel the deck wobbling beneath their feet yet. Until they do the New Zealand tradition of tinkering is as much as we're likely to do.