The Tohunga Suppression Act 1907 was intended to stop people using traditional Māori healing practices which had a supernatural or spiritual element. It grew out of concern over the practices of some self-appointed tohunga who played on superstition often travelling from pā to pā claiming to cure all kinds of illness.

The influential Te Aute College Students’ Association was particularly critical, believing that tohunga might harm patients, and could hinder Māori progress. Tohunga also came under attack from the prominent Māori doctors Māui Pōmare and Te Rangi Hīroa (Sir Peter Buck).

The Tohunga Suppression Act was presented by Māori MP James Carroll and supported by the four Māori members of parliament. It was passed in 1907. The preamble to the Act read:

Every person who gathers Maoris around him by practising on their superstition or credulity, or who misleads or attempts to mislead any Maori by professing or pretending to possess supernatural powers in the treatment or cure of any disease, or in the foretelling of future events, or otherwise, is liable on summary conviction before a Magistrate to a fine not exceeding twenty-five pounds or to imprisonment for a period not exceeding six months.

There were few prosecutions under the Act, and few convictions – its main effect was to drive tohunga underground. In 1962, it was repealed.

The Act has also been viewed as a breach of the Treaty of Waitangi, as it challenged traditional Maori wisdom – considered to be one of the taonga (treasures) that Maori were promised under the second article of the Treaty.

However, on 2009, five people were convicted of the manslaughter of their family member Janet Moses after drowning her in a ritual after advice from a tohunga that she was suffering under a makutu, or Maori curse.