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This is by no means invariably the case, and some very poor legislation has not infrequently been the outcome - the Electoral Finance Act springs to mind as one example.
But, a small majority of Parliament having accepted the balance of scientific opinion that climate change is occurring and human behaviour is contributing to its acceleration, it has become too important a matter to be the subject of careless, inadequate or unbalanced law.
The Bill that is now proceeding through the House is a compromise, but one with much to commend it, although in itself the immediate effect of the legislation amounts to little enough.
It remains regrettable that the transport and agricultural sectors will not be brought fully into the scheme earlier than 2011 and 2013.
The latter also presents a political risk to Labour, whose vote is largely located in urban areas, since city dwellers will be unhappy to realise they will be subsidising farmers for their Kyoto obligations for several years, while at the same time paying such high prices for family staples.
The Bill can only be regarded as a starting mechanism, a small beginning for what will become a highly complicated and probably very expensive response to a scientific theory, and one that will have an economic impact on every household and business in the land, although it will have very little impact in reducing global warming.
But those who cannot accept the theory in global terms need to reflect on the beneficial environmental effects of the legislation in a strictly local sense.
We know that carbon production is damaging to the environment; this Bill sets out to reduce it.
While the initial impact will be far from felt heavily by the major contributors - agriculture and industry - householders and motorists will bear an immediate expense through higher costs.
Eventually, however, by setting limits on the amount of "greenhouse gases" that can be emitted, industries including agriculture that exceed their limit will have to buy credits from those which are under their cap, a "carrot and stick" approach whose true costs cannot be known with precision.
Many of those costs will be passed on, so ultimately most pockets will be affected.
The Bill also creates a new property right and with it, therefore, a proportion of winners and losers.
Electricity prices will be directly higher within two years, and carbon reduction targets for motor vehicles will add to travel costs.
So, too, will higher energy efficiency standards for new buildings and houses.
Some of these costs will be offset.
New Zealand First gained a one-off rebate on power bills in 2010 and cash payments for people on low incomes, pensioners and those receiving Working for Family tax credits to help them with these extra costs, as part of its support agreement.
The Green Party extracted a commitment for as much as $1 billion to be spent over 15 years to encourage household energy efficiency, such as the provision of insulation.
This subsidy, too, will be income-tested.
But the Greens did not win any significant improvements that would provide for better public transport, and thus reduce levels of car pollution.
Nor was the party able to gain a permanent halt to new fossil fuel electricity generation, or stop large-scale forest conversion for dairy farming.
The National Party has said this legislation goes too far, too fast, and says it would design its own scheme, introducing it to Parliament within nine months of taking office.
This is hardly credible, given the years of patient effort needed to devise the Bill now before the House.
More likely, if National needs the Greens to govern, it will merely tinker around its edges, perhaps attempting to delay even longer capping the greenhouse emissions from industry sectors.
That would mean taxpayers would find themselves paying unacceptably higher costs.
It is 11 years since the Kyoto Protocol was created and New Zealand committed to it.
That our politicians have failed over a decade to reach even a broad consensus on policy is deeply regrettable and does not augur well for public acceptance of the need for collective effort.