IT SOUNDS, admits Chris Finlayson, like a “pretty nutty” idea. Yet the new law that declares the Whanganui river, New Zealand’s third-longest, a legal person, in the sense that it can own property, incur debts and petition the courts, is not unprecedented. Te Urewera, an area of forested hills in the north-east that used to be a national park, became a person for legal purposes in 2014. And around the world companies, foundations and assorted units of government have legal rights and responsibilities independent of the people who staff them. All the same, New Zealanders have been joking about whether the Whanganui might now vote, buy a few beers (how old is it?) or be charged with murder if a swimmer drowns.

The law, which was approved on March 15th, stems from disputes over the Treaty of Waitangi, by which New Zealand’s indigenous Maori ceded sovereignty to British colonialists in 1840. The treaty was supposed to have protected Maori rights and property; it was observed mainly in the breach. In recent years the government has tried to negotiate settlements for breaches of the treaty with different Maori iwi, or tribes. For the Whanganui iwi, the idea of the river as a person is nothing new. The iwi professes a deep spiritual connection to the Whanganui: as a local proverb has it, “I am the river and the river is me.” The law acknowledges the river as a “living whole”, rather than trying to carve it up, putting to rest an ownership dispute that has dragged on for 140 years. When it was passed, members of the iwi in the gallery of parliament broke into a ten-minute song of celebration.

In practice, two guardians will act for the river, one appointed by the government and one by the iwi. Mr Finlayson, the minister in charge of negotiations tied to the Treaty of Waitangi, hopes the change will help bring those who do environmental damage to the river to book. Under the settlement the government will also pay the iwi NZ$80m ($56m) as compensation for past abuses and set up a fund of NZ$30m to enhance the “health and well-being” of the river. It is one of 82 deals that aim to remedy breaches of the treaty, including one with the Tuhoe iwi that made Te Urewera into a person.

Days after the law passed, an Indian court declared two of the biggest and most sacred rivers in India, the Ganges and Yamuna, to be people too. Making explicit reference to the Whanganui settlement, the court assigned legal “parents” to protect and conserve their waters. Local lawyers think the ruling might help fight severe pollution: the rivers’ defenders will no longer have to prove that discharges into them harm anyone, since any sullying of the waters will now be a crime against the river itself. There is no doubt that of the 1.3bn-odd people in India, the Ganges and the Yamuna are among the most downtrodden.