Australia’s top court has thrown out a last-ditch attempt by the country’s most decorated soldier, Ben Roberts-Smith, to overturn a landmark defamation ruling.

Thursday’s ruling ends Mr Roberts-Smith’s long legal battle with newspapers he had sued over reports of serious misconduct while he was deployed to Afghanistan.

A judge in 2023 ruled that news articles alleging the Victoria Cross recipient had murdered four unarmed Afghans were true, but he argued the judge made legal errors.

It was the first time in history any court assessed claims of war crimes by Australian forces. Mr Roberts-Smith lost an appeal against that judgement and was ordered to pay the newspapers’ legal costs.

Mr Roberts-Smith, who left the defence force in 2013, has not been charged over any of the claims in a criminal court where there is a higher burden of proof.

The 46-year-old argued the killings occurred legally during combat or did not happen at all. He claimed that his life had been ruined by the reports.

At the time the articles were published in 2018, Mr Roberts-Smith was considered a national hero, having been awarded the Victoria Cross – the highest military honour in Australia – for “the most conspicuous gallantry in action” during an operation to hunt for a senior Taliban commander.

His seven-year legal battle, which some have dubbed Australia’s “trial of the century”, has reportedly racked up tens of millions of dollars in costs – but ultimately failed to stop his fall from grace.

After the judgement against Mr Roberts-Smith in 2023, the Australian War Memorial in Canberra, where his uniform and a plaque commemorating his Victoria Cross medal are displayed, added text panel with context of his alleged misconduct and civil defamation case.

The museum confirmed in May, after he lost his appeal, that it would make further changes to the display.