"The Crown solicitor has reviewed your case and has concluded that there is insufficient evidence of negligence on your part which would establish a causal connection with the death of the deceased,'' he said.
Justice Brewer said the degree of negligence necessary to find a criminal charge was very high. "It goes well beyond mere carelessness,'' he said.
The case had also been reviewed by the Solicitor-General, who agreed there was insufficient evidence for Mr Kukutai to stand trial, Justice Brewer said.
Mr Kukutai was discharged on the charge of manslaughter.
Riverlands Adventures faces charges brought by the Ministry of Business, Innovation and Employment (MBIE) in relation to breaches under section 16 of the Health and Safety in Employment Act 1992.
A hearing will be held next month at Manukau District Court.