Liberal senator Jacinta Nampijinpa Price “trampled” on the reputation of a prominent Indigenous leader without caring whether her claims were true or false, the Federal Court has heard in a high-stakes defamation battle.

Price fronted the Federal Court in Darwin on Monday for the first day of the defamation case, which was filed against her by Central Land Council chief executive Les Turner. She is expected to give evidence during the seven-day trial.

Turner, who launched the proceedings against Price in September last year, alleges Price defamed him in a media release published on her website and emailed to almost 2000 journalists in July that year.

He was not named, but Price said in the document that an unsuccessful motion of no confidence had been moved against “the CEO of the Central Land Council”.

Turner is represented by Sydney barrister Sue Chrysanthou, SC. In her opening address to the court, Chrysanthou said Price had “contradictory and unclear information from only one source” at the time the media release was issued.

A second source “had no first-hand information at all”, Chrysanthou said.

“To this day, Senator Price has never publicly admitted that what she said was wrong. She’s never made any apology for it,” Chrysanthou said.

“Despite being confused, despite having inconsistent information … the senator ploughed ahead and gave the thumbs up to her staff to publish the press release.”

There was “no explanation as to why it had to go out so urgently on a Sunday night”, Chrysanthou said.

“She trampled on my client’s reputation … without caring at all whether what was said about him was true or false.”

In documents filed in court, Turner says the media release conveyed a number of false and defamatory claims about him, including that he “no longer had the support of the majority of Central Land Council members because of his unprofessional behaviour in that role”.

Price admits this claim was conveyed, and is not seeking to prove it is true. Instead, she is seeking to rely on the defence of qualified privilege, which protects publications of public interest where a publisher acted reasonably. Reasonableness is expected to be the key battleground in the case.

Price has said the litigation could “cost me my seat in parliament” if she lost and was bankrupted because she was unable to pay damages and legal costs.

Under section 44 of the Australian Constitution, members who are undischarged bankrupts or insolvent are ineligible to sit in parliament.

Price started a crowdfunding campaign for her legal bills earlier this year. She disclosed in the parliamentary register of interests in September that Australia’s richest person, Gina Rinehart, had made a contribution to the legal fund via her company Hancock Prospecting.

The total value of all donations has not been revealed but only those above a $300 threshold must be disclosed. In light of that threshold, the donations from more than 700 donors total hundreds of thousands of dollars to date.

Chrysanthou said Price made no attempt to contact the Central Land Council or Turner before issuing the release and had “no excuse” for that failure.

The Country Liberal Party senator had originally sought to rely on a wider range of defences, including truth, but those defences were dropped before the trial.

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