Loss of the right to know when a product contains GM ingredients could quickly slide into effective loss of the right to choose everyday foods that are not genetically modified. Instead of it being the norm for food companies to strive to keep GM out of their products, this could become the preserve of niche eco brands.
The reason Washington wants to stamp out all mandatory labelling is plain: the US is the world's largest producer of GM crops and its soy and corn are now almost all genetically modified.
As more countries adopt mandatory food labelling regimes, US exporters must either secure market acceptance for GM products - or remove requirements that make them visible and avoidable.
While labelling underpins the ability to choose, and that choice is regarded as a consumer right in countries such as New Zealand, the US decries labelling as a "trade barrier".
Five countries in the free trade talks have mandatory labelling, and the US government and the biotech industry view the trade deal as an opportunity to bring Pacific Rim countries into line with US trade objectives. New Zealand's chief negotiator has identified its genetically modified organism regulations as one of "the top local impediments" to concluding a TPP agreement.
"It is well known", a diplomatic cable released by Wikileaks reports him saying, "that Monsanto does not like New Zealand's genetically modified organism regulations".
New Zealand's regulatory regime for genetically modified foods and organisms in the environment has been hard won.
The use of GM in food has been the most controversial and widely debated new technology of the last two decades.
That the country continues to avoid growing any genetically modified organisms for commercial production reflects sustained concern about the long-term consequences of taking the GM path and risks to the nation's brand in key export markets.
Washington knows this: US embassy cables repeatedly report that New Zealanders "do not readily embrace the technology" and "have tended to avoid such foods". The country's GM-free food producer status is increasingly becoming part of New Zealand's identity, just as its nuclear-free stance defines it.
However, unlike the nuclear issue, which is no longer considered an obstacle to closer ties, there is no sign that the US is willing to overlook New Zealand's GM policies.
While US objectives are abundantly clear, New Zealand's response is not.
National has stated it does not propose to weaken the law governing environmental release of GMOs while Labour and the Greens propose additional protections. The separate labelling law also appears to be broadly supported - so it is not that the US is pressing for something that is waiting to happen on either count. The question is whether the incoming government will stand up to pressure from the US to weaken our law as a trade off in TPP negotiations.
As the deal does not need to be brought before Parliament before the text is set, New Zealanders are entitled to know now whether GM food labelling will be protected as a bottom line. If New Zealanders are to be assured of a continued right to know about the presence of GMOs in their food, then a clear commitment is required from potential future governments that negotiators will have no mandate to "trade away" GM regulatory protections.
Without that commitment, the ability to have a food supply essentially free of GMOs is on the block.
Stephanie Howard and Simon Terry are researchers for the Sustainability Council of New Zealand, a public good NGO.
