She noted that many readers who have written to newspaper forums on the issue seemed to have confused AMD with euthanasia.

'For AMD, you die as a result of the natural disease you're suffering from,' she explained.

'For assisted dying (euthanasia and assisted suicide), you're doing something to hasten the death, so it's death by artificial means.'

It's important that people know the difference, Dr Chan added.

'While some may see a very thin line, it's still a line and we must be careful not to cross it.

'Allowing someone to die from a disease is different from deliberately helping the person to die.'

How can the public be educated?

Madam Halimah feels that healthcare professionals are the best people to do it.

'But now, because of restrictions in the AMD Act, they are not allowed to actively discuss AMD with patients,' she said.

The Act bans doctors and nurses who are caring for the patient from asking whether or not the latter has made or intends to make an AMD.

A doctor can ask for a search of the AMD register only when his patient is terminally ill and already unconscious and would need extraordinary life-sustaining treatment.

These restrictions prevent the public from knowing more about AMDs, Mr Khaw said.

So is it time to pull the plug on some of these obstacles?

Yes, Mr Khaw said.

He proposes two changes to the act. First, make it easier to sign up for an AMD by removing the need for a doctor to be a witness. Second, remove the restrictions that have made AMD a taboo subject between doctors and patients.

It is especially important to educate the young, Madam Halimah said.

'Older people are not likely to understand AMD, so the young must talk to their parents. This can also get young people to start thinking about AMD for themselves.'

Additional reporting by Lediati Tan, Elaine Yeo and Eoin Ee

1) Euthanasia: Doctor pulls plug

Euthanasia, also called mercy killing, is an active act of making a patient die.

It is one of two forms of assisted dying, the other being assisted suicide.

Dr Noreen Chan said: 'In cases of euthanasia, a third party performs the act that kills.'

In countries where euthanasia is legal - Belgium and the Netherlands - the act has to be done by a doctor, Dr Chan said.

2) Assisted suicide: Patient pulls plug

In an assisted suicide, the patient performs the act that kills him, while the doctor provides the lethal prescription.

Assisted suicide is legal in Switzerland and in the US states of Oregon and Washington.

In Switzerland, the 'assistance' does not have to come from a doctor, Dr Chan said.

In 2006, an Australian woman complied with his 71-year-old Alzheimer's-stricken partner's wish to die by handing him a deadly dose of drugs.

Last week, she was sentenced to spend several days a week in jail for nearly two years. Assisted suicide is illegal in Australia.

3) AMD: No plug to pull

An Advance Medical Directive (AMD) is a legal document you sign in advance to inform your doctor (in the event you become terminally ill and unconscious) that you do not want any extraordinary life-sustaining treatment to be used to prolong your life.

It is illegal for anyone to force you to make an AMD against your will.

Under the AMD Act, an AMD can be executed only when the patient is diagnosed with a terminal illness, needs extraordinary life-sustaining treatment, and cannot make a rational decision.

Palliative care, and food and water, still have to be given to the patient.

Over 10,100 Singaporeans have signed AMDs since the Act was passed in 1996. Over the years, 19 have been revoked and six have been put into effect.