Back in the day, when Trade Minister Tim Groser was just another diplomat assisting World Trade Organisation negotiations, he had to run a committee involving five big nations on a deadlocked issue.

Applying the "dark arts of trade negotiation", he inserted a different minor error into each of the five drafts distributed. If anyone leaked, he'd know who it was.

While NZ First leader Winston Peters may claim that WTO negotiating documents are always made public, the truth is those documents themselves are the product of negotiation, and negotiations involve secrets.

No-one starts a Trade Me auction with their best price.

So, that's No 1 in a list of the things that opponents of the Trans-Pacific Partnership agreement don't want you to understand. The secrecy surrounding TPP negotiations is typical of any such exercise.

No 2: The bogey of corporations being able to sue governments is not only overblown, but corporations can do that now, without a TPP. Look across the Tasman, where Big Tobacco is suing the government over its plan to enforce plain packaging for cigarettes.

No 3: Corporations might try to sue but they'll be whistling if the government is acting in the public interest. Raising new taxes, protecting the environment, or regulating for public-health reasons won't be excuses to mount court action.

No 4: United States corporate interests are obviously among those seeking influence on the TPP agenda, but that doesn't mean the US Senate and Congress are on board. That's why US President Barack Obama is having such trouble getting "fast-track" authority to negotiate TPP.

No 5: US politicians know less about what's in the TPP negotiating documents than US corporate lobbies. So it must be a plot, right? Well, actually, no. Politicians in the US, and in New Zealand for that matter, can agree to maintain confidentiality and be briefed on whatever they like with respect to TPP. Labour's trade and foreign affairs spokesmen, Phil Goff and David Shearer, avail themselves of this benefit. They support TPP, along with Shane Jones and some other Labour heavy-hitters, even if leader David Cunliffe is a leaf in the wind as he tries to balance what he knows is right and what his backers on the Left of the Labour Party expect.

No 6: No-one knows what the TPP could be worth to the New Zealand economy, so the Sustainability Council is right to question the $5.16 billion figure the Government has used, based on estimates from the internationally respected Peterson Institute, and peer-reviewed by an independent local bastion of credible number-crunching, the New Zealand Institute of Economic Research.

And Groser agrees. He doesn't put much store in econometric modelling of trade deals under negotiation, partly because they can underestimate benefits as much as be too optimistic.

For example, officials saw little value in the 30 year-old Closer Economic Relationship agreement with Australia, whose value is a no-brainer today. And growth in trade with China has exponentially exceeded projections for the six-year-old China-New Zealand free-trade deal, which incidentally includes its own version of TPP's feared "investor-state dispute settlement" provisions.

No 7: The US is railroading its agenda because it's just a big bully. That's not what you get from reading the Wikileaks versions of negotiation drafts. They show the US on the backfoot on many of the most contentious issues. US media reports suggest the US is under pressure from emerging economies involved in the TPP to weaken environmental protections it would like to insist on. As far as some poorer countries are concerned, regulating for the environment is just rich-country code for new ways to block market access and keep them poor.

No 8: This is the end of Pharmac. Balderdash. How many times does Groser have to back New Zealand's gutsy, Labour-led approach to ensuring the country has the cheapest versions of modern medicines it can get? That's a bottom line. We're not signing if Pharmac's compromised.

No 9: The deal will be done behind closed doors. It can't be. Every Parliament of every country involved will have to ratify any deal signed by leaders. That could take years. It will ensure public scrutiny of the detail.

No 10: It's a done deal. Tell that to Groser and Mike Moore and every other politician who ever wasted a chunk of their lives trying to negotiate the Doha Round of the WTO negotiations. The Doha failure is one of the reasons that regional rather than global trade-agreement efforts, like TPP, have emerged. There's no guarantee TPP will come in to land. And if it doesn't, that will be a shame for New Zealand, which has done so well from the liberalisation of trade as an exporting nation and suffered such grievous discrimination when locked out of the world's wealthiest markets.

- BusinessDesk

Jane Kelsey has written a rebuttal column to this. Read it here.