UPDATED 11.46AM: Christchurch woman with terminal lung cancer will speak at a hearing today supporting a petition to change New Zealand's euthanasia laws. 

A parliamentary committee is investigating public attitudes to voluntary euthanasia in response to a petition by former Labour MP Maryan Street.

Shirley Croll, 81, was diagnosed with lung cancer in January and was told that she had three months to live. 

She admits knowing that she'll die soon. 

"The beliefs suddenly come into an urgent reality," she said. "I think I've lived pretty well, but I want to die well as well."

Croll's husband died from motor neuron disease 19 years ago. She said the pain became so unbearable that he gave up eating and drinking.

"And it took eight really harrowing days for him to die, and it just seemed to me to be cruel that he couldn't have died straight away when he made that decision."

Stuart Armstrong, 56, has terminal bone cancer and told the hearing that he doesn't want to let his illness win, and doesn't want to endure the "wracking, hopeless miserable death that bone cancer is going to give me."

Armstrong said the cancer rob him of walking his daughter down the aisle one day and he'll never get to meet his grandchildren.

The hearing comes after it was revealed that police in Lower Hutt had set up an arbitrary drink-driving stop to collect details about elderly people leaving an Exit International meeting last month.

Seven cars were stopped, and the details of ten people were recorded.

Paul Basham, Wellington Area Commander Inspector, said the checkpoint was part of an investigation into aiding and abetting suicide begun after the Coroner referred the death of a woman in June to police.

He says the woman had a Class C drug in her system, but wasn't suffering a terminal illness.

"Our inquiries have identified other deaths that require further investigation with respect to the serious offence of aiding and abetting suicide," Basham said.

Police referred themselves to their watchdog, the Independent Police Conduct Authority.

Privacy Commissioner John Edwards is considering whether to also launch an investigation.

"I've heard suggestions that the purpose of the unit at the stop was misrepresented to individuals. I take a pretty dim view of collecting information on false pretences," he said.