Like so many others, we are deeply saddened by this setback, and more determined than ever to fight for the humane and compassionate treatment of vulnerable refugees.

Dr Kerryn Phelps, the medical professional and former independent MP for Wentworth, who fought so hard for Medevac, ends her eloquent piece in the Guardian (December 6) with these words of encouragement for those who remain on Nauru and PNG: "Please know this.

"There are many, many Australians of good heart who understand your plight and will continue to fight on your behalf not only for your medical care, but for a future for you in freedom and safety."

Before the landmark Medevac bill was passed, refugees held in offshore detention in Papua New Guinea and Nauru could only be transferred to Australia for proper medical treatment when a condition had become life-threatening.

Such transfers had to be defended in court cases that spanned months and years.

Sick refugees waited two to three years on average for medical transfer. Some people waited five years.

Twelve people died in detention over the past five years and some of those deaths were preventable.

The Medevac legislation put medical decisions back into the hands of doctors.

It meant that medical transfers could be triggered by the recommendations of two independent doctors who believed the patient could not receive adequate care in PNG or Nauru.

The Minister of Home Affairs, Mr Peter Dutton, then had 72 hours to refuse a medical transfer on character, security or medical grounds.

If the objection was medical, an eight-person medical panel would review the case. In the event they agreed with the initial medical decision, the Minister could still refuse transfer on character or security grounds.

The Medevac law only applied to refugees currently in PNG and Nauru, making a nonsense of the oft-repeated argument that it would provide a pathway for new asylum seekers to settle in Australia.

Despite the Coalition Government's assertion that Medevac creates a security risk, polling shows that 25 per cent of voters believe the Medevac legislation wasn't compassionate enough, and a further 37 per cent argued that the law struck a good balance between humane treatment of refugees and strong borders (Guardian Essential, Nov 25).

Doctors' support for Medevac is overwhelming, and some of the voices that ring loudest are those who have seen conditions on PNG and Nauru first hand.

Dr Nick Martin, a GP and former senior officer on Nauru, writes (Guardian, December 4) that the 'rates of physical and mental suffering in this retained cohort used effectively a human shield are unbelievable.

To know it is all so preventable is just heartbreaking.'

What is the purpose of this needless and expensive cruelty? It doesn't make Australians safer.

It doesn't save anyone's life at sea.

The only explanation is that the Morrison government believes it can win elections by being tougher and meaner than the other mob.

Australia is a nation of migrants.

We pride ourselves on 'the fair go'.

It's time to reinstate Medevac.