Alan Jones has failed to lift an injunction preventing him repeating defamatory statements against a Queensland family he and his employers were made to pay $3.7 million.
Toowoomba's wealthy Wagner family was awarded the record Australian defamation payout last year after Jones unlawfully claimed they were responsible for 12 deaths in the Lockyer Valley floods.
On Friday, the Court of Appeal upheld a decision by the Brisbane Supreme Court to prevent Jones, his Sydney radio station 2GB's parent company Harbour Radio and Brisbane station 4BC repeating statements defaming the Wagners.
Jones claimed the injunction unduly restrained him because it prevented "me and all staff at 4BC and 2GB from discussing most aspects of the decision or a defence of the case in any detail".
"The other side can go open slather," he said in a letter to a newspaper 10 days after the defamation judgment.
The Wagners' legal team opposed lifting the injunction on the grounds Jones would defame the family again.
But Jones' barristers claimed such an injunction against a media organisation was exceptional and there was no proof the veteran shock jock would repeat the defamatory statements.
In ordering the gag, Justice Peter Flanagan noted that in giving evidence in the trial, Jones maintained the Wagners were responsible for the 2011 tragedy near Toowoomba.
Jones claimed a tsunami-like wave consumed the town of Grantham after a wall of a quarry owned by the Wagners collapsed.
Court of Appeal Justice Hugh Fraser agreed there was an "overwhelming case" for the gag because Jones would likely again double down.
"Despite the ... very large award of damages, there is a real risk that Mr Jones may repeat gravely serious and very hurtful defamatory matter" Justice Fraser said on Friday.
"Such as risk is to be inferred from the apparent strength of Mr Jones' motive to injure the respondents' reputation, the endurance of which is evidenced by Mr Jones' conduct when giving evidence."
Justice Fraser also denied the injunctions prevented Jones discussing the judge's reasons.
Justice Flanagan found Jones and his co-defendants' defamatory comments were "extremely serious and of the gravest kind" and caused "profound personal hurt and harm to (the Wagners') reputations".
He found Jones and his co-defendants could not defend the defamatory comments.
Australian Associated Press