MEMBERS of a wealthy family suing radio host Alan Jones for defamation over deadly flood claims will have to work with broadcasters to figure out where the case goes next.
Denis, John, Neill and Joe Wagner sued Mr Jones, Radio 4bc Brisbane, journalist Nick Cater, and Harbour Radio over comments made after the devastating January 2011 Queensland floods.
The question of the role of the Wagner-owned Grantham Quarry in the floods will be pivotal to the determination of the dispute.
Justice Peter Applegarth said there is an "essential sting" to what the Wagners claimed were defamations.
The Wagners argue the broadcasts contained "imputations" that wrongly suggest they were to blame for the deaths of 12 people, or for the deadly flood when a quarry wall or levee breached or collapsed.
But lawyers for Mr Jones, Mr Cater and the radio companies rejected claims those meanings were in fact conveyed in the broadcasts.
A newly-published Brisbane Supreme Court decision showed the case was stuck on disputes about what "expert opinion" might be needed to address the lawsuit's major issues.
Issues for experts to weigh in on might include "hydraulic and hydrological phenomena" in Helidon and Grantham, Justice Applegarth said.
The Wagners' lawyers said experts should look at whether the existence or breach of the Wagner-owned Grantham Quarry embankment caused or contributed to the flooding.
The family members also wanted experts to look at whether the existence or breach of that embankment "had a material impact on the damage" the flooding caused.
The Wagners' proposed assumptions include a "no breach" scenario.
That would "assume that the embankment remained fully intact throughout the flood," Justice Applegarth added.
Lawyers for Mr Jones, Mr Cater and the radio stations proposed the experts be asked a series of questions.
But the two sides could not agree on what issues the expert evidence should focus on, Justice Applegarth said.
Topics such as the timing and way the embankment was breached needed to be sorted out, Justice Applegarth said.
He told the parties to work out which issues and assumptions would need expert opinion.
The case will be reviewed on September 14.
As NewsRegional previously reported, a 2014 commission of inquiry cleared the Wagners of responsibility for the floods.
Mr Jones has maintained his actions were those of a journalist acting in a community's best interests after the tragedy.
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