Rinehart's children get control of $5b

John Hancock speaks about the court rulings in Sydney. Picture: Sharon Smith/ The West Australian

Gina Rinehart's two estranged children have won the battle to wrest control of a family trust estimated to be worth $5 billion after their mother used "influential connections" and strategies close to "intimidation" in her failed legal fight against the siblings.

Australia's richest woman has also been ordered to open the books and account for her handling of the trust over the past nine years. The trust was set up by her late father, iron ore magnate Lang Hancock, in 1988.

A NSW Supreme Court judge yesterday dismissed claims that Mrs Rinehart had acted improperly in 2006 when she agreed to changes to the trust.

Justice Paul Brereton said Mrs Rinehart had demonstrated that she was prepared to go to "extraordinary lengths" and capable of exerting "enormous pressure" to retain control of the trust.

Justice Brereton ordered that Bianca Rinehart be appointed trustee of the Hope Margaret Hancock Trust as the "better-suited" candidate to replace her mother and in preference to Mrs Rinehart's push for an independent company to take the reins.

The legal action was launched by Mrs Rinehart's three oldest children - Bianca, John Hancock and Hope Welker - in 2011.

Mrs Rinehart was supported by her youngest daughter _Ginia. Ms Welker dropped out _ of the action, leading to her being joined as a defendant.

"She (Mrs Rinehart) procured Hope's withdrawal as a plaintiff by making her 'loans' of some $45 million, in consideration for which she also acquired, for her lifetime, such voting rights as Hope might become entitled to in HPPL," Justice Brereton said.

He said that after repeatedly seeking to delay and dismiss the case during two years of litigation, Mrs Rinehart announced seven days before a hearing into her removal as trustee that she would step down. The dispute then turned to who would replace her as trustee.

Justice Brereton's decision describes Mrs Rinehart as using "influencing connections" and measures that in some cases "closely approach intimidation" in efforts to deter her children from the legal action.

He said lawyers threatened Bianca that she would be sued for "enormous damages" and she faced unsubstantiated accusations of "unlawful and dishonest conduct".

"These were most grave allegations and they were raised and pressed in a manner calculated to intimidate Bianca," Justice Brereton said. "I have never seen such pressure exerted, so persistently, on a litigant as has been apparent in this case."

Mr Hancock said yesterday the case had involved enormous pressure but there was no choice but to see it through. He cited pressure from politicians, including a September 2011 email from Nationals senator Barnaby Joyce, whom he had never met, to Ms Welker.

"We've been under enormous pressure for the last four years and some of the worst was from Barnaby Joyce sending an email from his government address to my sister Hope, trying for her to drop the court case," Mr Hancock said.

"And after the judgment, I think some questions need to be raised on why Barnaby wrote this email."

A spokesman for Hancock Prospecting said the company was pleased the challenge to the amendments to its constitution was rejected.

Yesterday's decision is not the end of the family's legal stoush, with a separate battle in the Federal Court over mining assets worth up to $10 billion listed next month.