Lawyers for victims of sexual abuse say the Catholic Church has used a legal technicality to reduce compensation payouts to their clients.

The Church argues its assets are held in a property trust that cannot be held liable for historical cases of abuse.

It leaves sexual abuse victims with no-one to sue.

Lawyers are calling on the church to stop using what's known as the 'Ellis defence', and there are moves underway in New South Wales to have the defence overturned.

Lawyer Angela Sdrinis, who represents victims of historical sexual abuse, says the Ellis defence has been a factor in about 50 of the cases she has been involved in.

"It's certainly the case that the Church offers less money because of this defence. It is the case that it's more difficult to negotiate with them," she said.

"I mean, a lawyer's ultimate weapon is to be able to say to your opponent 'We'll see you in court,' and that's just not an option in these cases."

The Church says, in the Melbourne Archdiocese at least, the defence has not led to reduced payouts.

But another lawyer who specialises in abuse claims, Dr Vivian Waller, estimates there are hundreds of cases across Australia where victims have had to accept negotiated settlements, because the defence means their cases will never make it to court.

Sorry, this audio has expired Ellis defence 'reducing compo payouts'

"I don't know of any other organisation that would say it is not possible to hold them to account for their actions on the basis that they're not really an entity, not a legal entity at all and can't be sued," she said.

"I find it quite extraordinary, and I find it morally bankrupt."

The Church says the Ellis ruling reflects the High Court's view, and while the church must comply with its legal obligations, it is equally entitled to legal protection.

The Church and its religious orders have long argued that there is no-one victims can sue in cases of historical abuse - the perpetrators have often died, and those now in positions of power cannot be held responsible.

And the Church's assets - estimated to be worth billions of dollars - are held in various property trusts, which the courts have ruled are not liable for the conduct of clergy members.

The Ellis ruling is named for lawyer John Ellis, who finally cemented this defence when he tried to sue the Church for the abuse he suffered as a boy.

He lost, after taking his case to the High Court in 2007.

Mr Ellis has represented many other victims in historical cases, and says the defence established in his own case is frequently used.

"It's always implied as a read between the lines. I have had lawyers for religious orders sit across the table from me and say 'Well, there is absolutely no liability in this matter'," he said.

Overturning the defence

Dr Waller is calling on the Church and its religious orders to stop relying on the Ellis defence.

"It's about time that the different parts of the Catholic Church took some kind of moral responsibility for their actions and stopped hiding behind technical legal defences and stopped trying to pretend that they don't exist," she said.

"I mean nothing could be more ludicrous."

New South Wales Greens MP David Shoebridge introduced a bill to Parliament earlier this month to try to overturn the defence in that state.

But he is worried the major parties will not back the bill.

"There is some concern that it won't get support because of the political influence the Catholic Church has here in New South Wales politics," he said.

"But that being said there are people of goodwill on this issue from all sides of politics."