The advice, provided to the Greens leader from Hobart criminal lawyer David Gunson in April, says that a doctor who ``by the administration of a medical service intended to reduce or temporarily relieve a terminally ill patient's suffering, knowingly hastens the death of the patient'' would be liable for murder.

``To put it simply, if a medical practitioner knowing that a patient is likely to die because of the existence of terminal disease hastens the death of that person to prevent further suffering, that medical practitioner commits the crime of murder,'' Mr Gunson said.

According to a retired Northern doctor, that means most doctors who have delivered palliative care could be liable for the charge. Dr Helen Cutts worked on the North-West Coast until her retirement in 2001, and is one of 12 Tasmanian doctors on a public Doctors for Voluntary Euthanasia Choice directory.

She said it was considered good palliative care to offer ``terminal sedation'' as a treatment option to people for whom palliative care was not providing relief.

The practice involves increasing the morphine dose until the person is comfortable and is often explained as a double effect, where pain relief is the intention but death is another result.

 ``Most people call it slow euthanasia,'' Dr Cutts said.

``You know that by doing this they will die a day or two, or a few hours, or however much earlier than they would have done otherwise.

``A lot of doctors don't like admitting to themselves that's what they are going to do, and that's why they talk about the double effect.''

Dr Cutts said she supported the proposed Voluntary Assisted Dying legislation because it would provide legal protection for existing medical practice.

The legislation is set to be debated in Parliament next week, but is likely to fall at least two votes shy of a majority.

Mr McKim said the proposed laws, co-sponsored with Premier Lara Giddings, introduced safeguards on what in many cases was existing practice.

He dismissed concerns raised in a report by University of Tasmania academics Hanna Graham and Jeremy Pritchard that the risks of the reform were not justified, saying there could only be bracket creep on eligibility if a later Parliament reviewed the laws.