Dr Nitschke claims to have 25 terminally ill patients waiting to use his "death machine", including one from Britain. The first, Jan Culhane, a 51-year-old mother from New South Wales, travelled almost 3,000 miles across Australia to Darwin, in the Northern Territory, where she has gone into hiding.
Mrs Culhane is suffering from cancer, which began in her breasts and has spread to her lymph glands. In a written note, she described why she made the journey: "I want to die because I've got a terminal illness and because the quality of my life has been reduced. The last emphatic reason is that I will not live in fear."
If, as planned, the Northern Territory's Rights of the Terminally Ill Act begins operating on 1 July, Mrs Culhane will ask Dr Nitschke to connect her to his machine. It consists of a small suitcase containing two syringes of lethal drugs. One lead from the case goes to a laptop computer; another lead would go into Mrs Culhane's arm. The computer screen would present Mrs Culhane with a three-stage process, ending with the statement: "If you press YES, you will cause a lethal injection to be given within 30 seconds, and will die. Do you wish to proceed?"
If she does press Yes, compressed air will drive the first of the drugs, Nembutal, a barbiturate, into her arm and she will fall asleep within seconds. The second drug, a muscle relaxant, will follow. She would die painlessly from asphyxiation. Dr Nitschke has named his computer software Self-Deliverance.
There is a sense of the surreal as Dr Nitschke describes his preparations for the ground-breaking law in one of the world's last frontiers. The Northern Territory is a place the size of Europe with just 150,000 people. It was Marshall Perron, the territory's conservative former chief minister, who pushed the legislation through last year after witnessing his mother and a fellow MP die painfully.
The Act goes beyond similar provisions passed in the Netherlands and Oregon in the United States. To qualify, a terminally ill patient must have been examined by at least two doctors and a psychiatrist, who must confirm that the request to die does not arise from a clinical depression related to the illness. Then there must be a 48-hour "cooling-off period" before death process can begin.
The legislation has caused ructions among Australia's doctors. The Australian Medical Association has called for its repeal, saying that it takes no consideration of the ethical and moral obligations of doctors that life, however impaired, is worth fighting to save.
Chris Wake, the association's Northern Territory president, has launched a court challenge in a coalition with clerics and anti-abortion groups, claiming that the law is unconstitutional. He is unmoved by opinion polls which show that up to 80 per cent of people in many Western countries support legalised voluntary euthanasia.
"Why has every other government in the world, faced with such figures, come to a different conclusion to the Northern Territory government?" Dr Wake asks. "Because here, there is a peculiar immediacy about politics. That has bastardised the process."
Faced with condemnation by many of his peers, Dr Nitschke, 48, is something of a loner. He has received international messages of support on the Internet, as well as a letter from a 12-year-old girl in Birmingham describing him as "evil".
Most of those who have contacted Dr Nitschke about using his machine are middle-aged or elderly women with terminal cancer living in rural areas. "They're people who are used to being in control of their lives and not being patronised by the medical system," he says.
Dr Nitschke believes that many of his outraged colleagues are hypocrites, because some doctors already quietly help some terminally ill patients to end their suffering by withholding treatment or increasing doses of pain-killing drugs. Had he ever helped someone to die voluntarily? "I have to be circumspect because the Northern Territory is a predatory place. But the short answer is yes."
If the legal challenge blocks the new law, Dr Nitschke says: "It will put us back to a system of people trying to get their own drugs and doing bad jobs of trying to kill themselves. Back to the Dark Ages."