The much anticipated Trans Pacific Partnership trade agreement was signed yesterday but there is a long and difficult path ahead before it comes into force in about two years.
In New Zealand, the trade agreement must go through the Parliamentary treaty examination process.
The text of the agreement, together with a national interest analysis, will be presented to Parliament before passing on to the foreign affairs, defence and trade select committee.
The major roadblock will be the approval by the United States Congress.
President Barack Obama has made the TPP a legacy-defining issue but faces opposition from some Democrats because union supporters are worried about losing jobs.
Republicans are concerned their farmer supporters will not be happy with the removal of protection from agriculture.
The Obama Administration hopes the pact will help the US increase its influence in East Asia and help counter the rise of China, which is not one of the TPP nations.
Politicians in the US and other TPP countries must approve the deal.
Five years in the making, it would reduce or eliminate tariffs on almost 18,000 categories of goods.
Initial reaction from US Congress members ranged from cautious to sceptical.
The 12 Pacific Rim countries, including New Zealand and Australia, sealed the deal to create the world's largest free trade agreement.
The deadline was extended several times but the agreement capped five years of difficult talks led by the US.
The New Zealand Government will need to get the deal squared away before the next election in 2017 to ensure it remains intact.
Opposition political parties were united in their condemnation of most parts of the TPP.
Labour deputy leader Annette King said Labour had made it clear it would not support the TPP if it did not meet the bottom lines of meaningful gains for farmers, the ability to restrict house and land sales, protecting Pharmac and the ability to govern in the interests of New Zealand.
ExportNZ executive director Catherine Beard said it was a huge relief for New Zealand exporters the TPP had reached a positive conclusion, despite not getting all that was wanted from dairy access.
But First Union general secretary Robert Reid said the Government had betrayed the interests of working New Zealanders by signing agreement. The TPP was a threat to the country's sovereignty, he said.
Prime Minister John Key welcomed the deal and said the agreement would give New Zealand exporters better access to a market of more than 800million customers in 11 countries across Asia and the Pacific.
In particular, the TPP represented New Zealand's first free trade agreement relationship with the largest and third-largest economies in the world - the US and Japan.
Successive New Zealand governments had been working to achieve that result for 25 years.
The TPP had been a focal point of Mr Key's Government and Trade Minister Tim Groser has been used as the Government's main front man.
Mr Groser said yesterday the comprehensive agreement offered much better access for New Zealand goods and services in 11 important markets.
''TPP breaks new ground for us. We've seen from previous FTAs, including the China FTA, how positive they have been for New Zealand trade and investment and in supporting jobs and growth for New Zealand.''
Not being in the TPP would put New Zealand at a competitive disadvantage, Mr Groser said.
Tariffs would be eliminated on 93% of New Zealand's trade with its new FTA partners, once the agreement is fully phased in.
That would represent $259million of tariff savings a year - about twice the savings initially forecast for the China FTA, he said.
Dunedin intellectual property lawyer Sally Peart said there were three major areas of change for New Zealand: intellectual property, the effect on medicines, and overseas investment.
One of the biggest concerns before the end of the negotiations was the effect on subsidised medicines in New Zealand, Ms Peart, a principal in Marks & Worth, said.
''The US has been very keen to undermine Pharmac's ability to negotiate beneficial pricing arrangements.''
The agreement reached appeared to have not changed New Zealand's standard 20-year patent period - the monopoly period given to pharmaceutical companies to exploit new drugs.
But the terms of particular pharmaceutical patents could possibly be extended if there were unreasonable delays in examining the patent or getting regulatory approval, she said.
''This is unlikely to happen in New Zealand due to the speed with which New Zealand processes patent applications but it is a possibility.''
For the TPP, the US proposed an eight-year monopoly period which included five years of data exclusivity plus
three years of ''pharmacovigilance'' to keep cheaper versions off the market for eight years.
Australia, New Zealand and Chile had consistently opposed the move but appeared to have been unsuccessful, although it appeared details were still to be agreed, Ms Peart said.
