Mana Party leader Hone Harawira says the surveillance legislation passed by Parliament will allow police to spy on people without having to prove a crime has been, or will be, committed.
The Government's controversial Search and Surveillance Bill passed its final reading in Parliament on Thursday.
It will come into force in April, and will replace temporary police surveillance laws passed last year after a court ruling threw the right of police to take covert video into doubt.
Mr Harawira told Parliament people's right to silence will no longer exist and the liberties and freedoms enjoyed by the public will disappear.
"Enforcement officers can bug your granddaughter's phone, install a hidden camera in your daughter's bathroom, download the files from your wife's computer and steal your files without even having to prove that a crime has been, or will be, committed."
Justice Minister Judith Collins says the legislation brings search and surveillance powers up to date with 21st century technology.
But Ms Collins says a number of safeguards have been included in the bill.
"It now regulates an area which has been somewhat under-regulated in the past ... there are some people who would say that it puts too much in the way of restrictions on police."
The bill was passed by 61 votes to 57. National, ACT and United Future voted in support.