The complex battle that started in July pits Ms Rinehart's company Hancock Prospecting against the heirs of mining pioneer Peter Wright and engineer Don Rhodes over the massive Hope Downs mining complex amid allegations of decades-old contract breaches.
Mrs Rinehart's eldest children, John Hancock and Bianca Rinehart, are also involved in the case and claim their grandfather Lang Hancock left them a hefty share in the Pilbara mining resources he discovered in the 1950s that are now mined in partnership with Rio Tinto.
The pair sat in the Supreme Court public gallery in Perth on Monday as their lawyer Christopher Withers SC summarised their case rejecting Wright Prospecting's claim for Justice Jennifer Smith.
The trial has featured sensational claims against Gina Rinehart.
"The partnership was not in the business of building a mine and conducting mining operations," he said referring to Lang Hancock and Peter Wright's business partnership.
"After Peter (Wright) died it wasn't even permitted to be involved in mine management."
Wright Prospecting has demanded a share of unmined and mined Hope Downs tenements and royalties, amid a claim that Hancock Prospecting breached 1980s partnership agreements.
Mr Withers said the men's partnership did have the opportunity to acquire tenements that became the Hope Downs mining complex and Wright Prospecting gave up its 1987 contractual right to royalties.
"(Wright Prospecting's) case must be dismissed," Mr Withers said.
The Hope Downs mining complex near Newman is one of Australia's largest and most successful iron ore projects, comprising four open-pit mines.
DFD Rhodes is claiming a 1.25 per cent royalty share of Hope Downs' production, over an alleged deal with Mr Hancock and Mr Wright that handed over tenements in the 1960s.
Hancock Prospecting maintains it undertook all the work, bore the financial risk involved in the development at Hope Downs and is the legitimate owner of the assets.
About two dozen lawyers and company spin doctors have packed the Perth courtroom for the trial, which has also featured sensational claims against Gina Rinehart.
These include that the billionaire allegedly devised an unlawful scheme to defraud her children and threatened to have her father's former housekeeper Rose Porteous, who he later married, deported, and called her a "prostitute" and "oriental concubine".
The court has also been told Ms Rinehart lied about her father allegedly breaching his fiduciary duties to his company, and that Mr Hancock attempted to sever ties with his daughter in the years before he died in 1992.
Ms Rinehart inherited her father's iron ore discovery in WA's Pilbara region and forged a mining empire after he died.
She developed mines from the tenements at Hope Downs, signing a deal in 2005 with Rio Tinto, which has a 50 per cent stake in the project.
Her wealth is estimated to be about $36 billion and she is executive chair of Hancock Prospecting.
