"The Government would have to have a clear view for it to put it on its order paper.
Fundamentally it has to be confident it's got the numbers, and I couldn't be at all confident we've got the numbers. There would be quite a considerable portion of the National caucus that would vote against that. It is something best managed through that members process."
The fact Labour MP Maryan Street's euthanasia bill had been withdrawn recently, "won't stop someone putting another one in".
Mr Key said he wouldn't have supported Ms Street's bill, "because I think it went too far, but I think there are certain limited circumstances where it (voluntary euthanasia) would make sense".
Wellington regional coroner Mr Smith found committed euthanasia believer Edna Gluyas, 85, committed suicide in August 2011 having suffered arthritis and back pain for some time.
Mrs Gluyas' doctor, Don Barrett, said she showed no signs of depression.
Mr Smith found the widow had clearly been affected by the death of her golden retriever that year. Police were initially concerned that Mrs Gluyas might have had help to commit suicide, but after an investigation they determined she was capable of carrying out the process herself.
Mr Smith said euthanasia was a more appropriate term for Mrs Gluyas' "tragic death".
"Once again this death raises the vexed issue of euthanasia and ... it will be necessary for Parliament to address this matter yet again."