Between 1945 and 1985 almost 250 (242) nuclear weapons were tested in the Pacific. Many of these tests were conducted by France.
France conducted the tests at Mururoa (part of French Polynesia). Gradually New Zealand started opposing the tests, that the French were conducting. Through out the 1960's New Zealand had a National government, and they didn't want to upset the French by protesting. In 1972 New Zealand had a new primeminister and government. Kirk and Labour.
Why Kirk? In general New Zealand had opposed nuclear testing any where, as the dangers of it had become obvious in the 1950's. In 1963 New Zealand signed a treaty, The Test Ban Treaty. This was to try and control the development of nuclear weapons. New Zealand wanted the arms race to be consoled. New Zealand said, " it's wrong to test them (nuclear weapons) in our backyard, go back to France and test them if you must." There was a growing movement at this time to make the Pacific, nuclear free. Three Pacific countries tested weapons, China, USA and Russia. New Zealand saw themselves as a spokesman for the small countries in the Pacific.
Kirk decided to act. First thing Kirk did was he summoned the French ambassador and asked him to tell his government that, New Zealand wanted them to stop testing. Of course the French government wouldv'e said, " Mururoa is french territory, the testing is essential for our protection." French would also have claimed they had a right to test weapons, to defend themselves.
Second thing Kirk did. Working with Australia, they decided to take the French to court. They didn't go to a normal court they went to the world court, The International Court of Justice located in The Hague. Attorney General Findlay of New Zealand went on the behalf of the two nations. The court agreed with the arguement Attorney General Findlay put forward and issued an injunction. The French were asked to stop testing while the matter was investigated further. The French ignored the injunction and carried on testing.
Now New Zealand decides to up the pressure. New Zealand sends their navy northwards, The Otago and The Canterbury, with a labour mp on board and the Australians send a supply ship. The ships sailed around the test area. Although the French didn't admit it pressure from Kirk took its toll. In 1974 the French started to test under ground they said, " we have done enough tests in the air."