The Mount Waverley woman and her husband, who cannot be identified, are accused of keeping the woman as a slave between July 2007 and July 2015 when she was rushed to hospital in a serious condition.

The woman, now in her 60s, was emaciated, suffering untreated diabetes and weighed just 40kg when she was rushed to hospital, where she stayed for more than two months.

She first came to Australia on two six-month tourist visas to care for the Melbourne couple's three children before being granted a one-month tourist visa in July 2007.

A month later the woman became an unlawful non-citizen and her passport expired in 2011, prosecutor Richard Maidment QC told the couple's Supreme Court trial.

But the wife's barrister Gideon Boas told the jury the expiry of her visa was central to the case, disputing that the alleged victim who had initially lied about working for the family did so because she believed she had been treated as a slave.

"You see, the alternative and far more plausible reason, we say she did these things is that the discovery of (the woman) by the authorities spelled serious trouble for both (the wife) and (the woman)," Dr Boas told the jury.

He said the woman was an integrated member of the family's household, referred to by the Tamil word for grandmother and seen in family pictures and on holidays with the family.

The alleged victim was interviewed by police six times and some of the details in her evidence are "colourful", Dr Boas said.

"The way that she says she was treated - abused, locked up, unable to speak to anybody - these are claims that come from her and they come from her alone," he said.

The wife has denied all allegations the woman worked in domestic servitude for the couple and their three children, and Dr Boas said even if some of the allegations stacked up the jury had to decide if it amounted to slavery.

"Even if (the woman) was brought here to work, to serve, that does not amount to slavery," Dr Boas said.

"The law is clear. Harsh and exploitative conditions of labour may be conditions of slavery but do not themselves amount to slavery."

The husband's barrister John Kelly SC told the jury the trial was essentially two entirely separate cases against his client and the wife.

He said the woman had described the husband as being supportive of her, someone who "mucks in with the chores" and worked extremely hard.

Mr Kelly said the alleged victim was interviewed six times by police, had given evidence in court previously and "very often" it was the wife she spoke about.

"Evidence regarding one accused is not necessarily the same as evidence against the second," he said.

Australian Associated Press