The lawyer who led two successful private prosecutions for forestry deaths says the decisions vindicate a union campaign.
The Council of Trade Unions (CTU) has won a second private prosecution against the employer of 19-year-old Eramiha Pairama, who was killed by a falling tree near Whakatane in January 2013.
Last week the CTU won a similar case against the employer of a Tokoroa loader driver, Charles Finlay.
The Ministry of Business, Innovation and Employment did not prosecute either case despite 10 forestry deaths in 2013.
Nigel Hampton QC, who led the cases, said they demonstrated that the regulator had not been doing its job, and forestry companies were not being rigorous enough in protecting their employees.
"They've demonstrated that the regulator was not doing the job it should have been doing, and that the forestry owners and contractors were not applying rigourous enough standards to the health and safety of their employees."
Mr Hampton said Worksafe New Zealand, which is now the health and safety regulator, seems to have got the message.
Mr Pairama's mother, Selena Eruera, said she hoped the ruling showed employers they had to take accidents seriously.
"The contractor has been made accountable by the courts, and put the responsibility on the man that's supposed to be looking after my son, who my son trusted," she said.
Ms Eruera said she still had unanswered questions over her son's death.