Hitchcock called it the MacGuffin, the object or concept that set his plots in motion but isn’t especially important.

As the CPRS debate takes on a feeling of high — or at least medium — drama and the tension builds ahead of tomorrow’s Liberal party debate/self-immolation over whether to accept the government’s deal, the MacGuffin here is Copenhagen. Copenhagen is the reason the government insists that the CPRS issue must be resolved now. Copenhagen is the reason many in the coalition think the CPRS issue shouldn’t be resolved now. Both are wrong.

Copenhagen doesn’t matter at all to the CPRS debate, because there is already bipartisan agreement about the target range Australia’s negotiators will take to the meeting, and the CPRS — unlike the US schemes under consideration by Congress — is separate from Australia’s position on climate aid.

Not that we actually have a position on climate aid, other than that we think it’s really important.

There is, incidentally, an easy way for the government to get its CPRS through while making the coalition happy: negotiate an in-principle deal now that will be passed in February when the full legislative and regulatory framework is finalised (and, incidentally, post-Copenhagen). That would satisfy the Liberals, who insist they shouldn’t be voting before Copenhagen, and give the Prime Minister something to take there. After all, he has no more than the coalition’s word that it supports his target range of 5-25%, but that’s enough for him to give riding instructions to his negotiatiors.

But if you want to labour the metaphor — and few metaphors escape unlaboured round here — the entire exercise is a giant MacGuffin, because the CPRS has nothing to do with addressing climate change. It’s a political scheme, intended to enable voters to check off climate change on their list of concerns, and inflict maximum damage on the coalition. And by gum, it’s certainly succeeded on the second point.

The debate today and tomorrow about the CPRS deal is thus most easily understood if you completely divorce it from climate change and treat it as a vast financial game, the rules, internal workings and outcomes of which can be endlessly reconfigured for political effect.

The hardest workers in all this will not have been Penny Wong and Ian Macfarlane but the bureaucrats who have to cost up every reconfiguration, work out how to achieve them, and prepare instructions for the drafters at the Office of Parliamentary Counsel, the gurus who prepare government legislation. And all that has to be done while complying with all the usual policy and legislative requirements of the government, which are normally intended for issues being developed at a slightly more leisurely pace. Anything involving costs to the Budget have to be worked through and agreed with Finance and Treasury. Anything imposing legal penalties has to be run past the Attorney-General.

Unless they’re lucky, they’ll have to whip up new Regulatory Impact Statements (easily enough done, since the majority aren’t worth the paper they’re printed on). There’ll be letters to the Prime Minister and Treasurer flying around “copied to our colleague the minister for X”, and amendments once drafted have to put through the internal government wringer before being finalised for dispatch to the printer — they all have to be printed up before they can be introduced into Parliament. Some lucky officer in the Department of Climate Change will have to do a late night or early morning trip to the printer’s.

It’s at times such as these that all that pious talk about better policy practice and good internal process tends to go by the board. It’s a nightmare and ministers and their staff are usually oblivious of it. They tend to want to know why everything takes so long, despite the fact that it’s often the very processes they’ve put in place that slow everything down. For example, the CPRS amendments will have to be run past the caucus sub-committee responsible for climate change, or at least its chairman, Tony Zappia, before they go into caucus for approval, even though that approval is virtually pro-forma even for highly controversial legislation.

All for an entirely confected timetable for a purely political piece of legislation.

At this point either the government has gone as far as it will go, or it has the basis of an agreement with Macfarlane and therefore Turnbull. It seems like the latter. Once it is formally signed off by cabinet and caucus tonight, it is then handballed to Turnbull to get it through his party tomorrow. It seems like he has the numbers to get it through, but the issue is how much damage that will inflict as he does it, and how good he is at repairing the damage. Turnbull isn’t good at either minimising damage or repairing it afterwards, certainly not where people are concerned. Indeed, his instinct is to inflict maximum damage on his opponents, regardless of their feelings. He’ll have to restrain that urge like never before tomorrow morning.