A disabled woman who was sexually abused by her priest has spoken out against the Catholic Church for relying on the so-called "Ellis defence" to fight her legal claim.

Jennifer Herrick says the church is still using the controversial legal precedent to block victim's claims, despite Cardinal George Pell telling the child abuse royal commission that victims should be able to sue the church.

Ms Herrick was a shy 19-year-old with a severe physical disability when her local priest, Father Tom Knowles, struck up a friendship with her.

"He made me feel normal, he made me feel like my walk didn't matter," she said.

Ms Herrick says when she was 22, Father Knowles initiated sex with her. It was sudden and painful and she felt powerless to stop him.

"I had no idea who to turn to, who do you turn to for something like this?" Ms Herrick said.

Father Knowles maintained a secret sexual relationship with Ms Herrick for 14 years. She says the sex was hurried and humiliating, often taking place in public places or in his car.

He ended the relationship by telling her he had just been "experimenting".

"I lost everything, career, I didn't have a family, no children, lost my job, lost my superannuation. I'm really really behind the eight ball," Ms Herrick said.

In 2011 she complained to the Blessed Sacrament Fathers Order and it admitted Knowles had behaved inappropriately. She was offered $100,000 in compensation and says she took it because she was about to have surgery and her mother was gravely ill.

She now wants a full hearing of her claim for damages in the NSW Supreme Court, but the church's lawyers have told her it will be relying on the Ellis defence in the case.

'Ellis defence' rules the church not liable for actions of priests

At the heart of the Ellis defence in a court ruling that the church is not liable for the actions of its clergy.

It came about in 2007 when former altar boy John Ellis tried to sue an abusive priest, the church and the then Archbishop, Cardinal Pell.

Mr Ellis sought damages for abuse he suffered at the hands of Father Aiden Duggan in Sydney in the 1970s.

The NSW Court of Appeal found that the church's assets are held in property trusts, which are protected from law suits regarding the behaviour of clergy. Those trusts are worth billions of dollars.

In March, Cardinal Pell told the royal commission on child sexual abuse that victims should be able to sue the church.

"I believe the public were given the understanding that this was not the correct path," Ms Herrick said.

"But in my case, it's still happening".

Greens MP and victim's group question use of Ellis defence

Greens MP David Shoebridge has introduced a bill in the New South Wales parliament which seeks to overrule the Ellis defence.

He says it creates a shield to protect church assets from legal claims.

"They sit down opposite the victim and they say 'sorry about what happened to you but have you heard of the Ellis defence you can't win this case and we're willing to offer you a discount'," he said.

"What we have got from Cardinal Pell was a series of statements that if you took on face value should say the church should never again run the Ellis defence.

"What Cardinal Pell says to the royal commission is very contrary to what he has done as a manager of church finances. The fact is the law hasn't changed. These statements have been made but all the power continues to reside with the church."

Victims' group Broken Rites says Father Knowles' behaviour should be viewed in the same light as doctors who had sexual relationships with patients.

In a statement to the ABC, Father Graeme Duro from the Blessed Sacrament Fathers said Ms Herrick's case is "nothing like" the Ellis case because he sued parties who were found by the court to have had no role in appointing or supervising the priest.

"I wish to add that the Congregation has sought at all times to deal fairly and openly with Ms Herrick," he said.

"She initially raised her complaint through Towards Healing and a settlement was reached. We deeply regret that having reached a settlement with us, she is now seeking to overturn that settlement. We hope that these matters will reach a rapid resolution through the courts.

"As the matter is before the courts we are constrained in what we can say but the essential point is that Ms Herrick has named a number of parties to her proceeding.

"One of them had no role in appointing priests but a number of others did, and those that did admit that they did. It is a matter for the courts to determine whether any of the defendants have any liability to Ms Herrick".

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