The Daily Telegraph’s reporting of allegations against Geoffrey Rush is “the most recklessly irresponsible journalism that has come before a court in this country”, the Oscar-winning actor’s barrister has told a court.

Rush’s barristers, Bruce McClintock SC and Sue Chrysanthou, began their closing address to the court on Thursday as the almost three-week long defamation trial approached its conclusion.

McClintock told the federal court justice Michael Wigney that the Telegraph’s articles about Rush were “an example of reckless and indeed cruel irresponsibility”.

“The effect of these articles on my client … the destructive effect, is appalling,” he said. “Do they care? Did they think about what they were doing? The answer is clearly not.”

He said the Sydney paper had the “power to smash people’s reputations ... power to destroy their careers, without responsibility.”

“This is the most recklessly irresponsible journalism that has come before a court in this country,” he said.

Rush is suing the tabloid over a series of articles published in November and December 2017 alleging he had behaved inappropriately towards a castmate, Eryn Jean Norvill, during a 2015 production of Shakespeare’s King Lear.

One front-page story was headlined “King Leer” and featured a portrait of Rush in character.

On Wednesday the Telegraph’s barrister, Tom Blackburn SC, told the court Norvill had been an “utterly honest” witness who had nothing to gain from giving evidence against Rush except “stress and anxiety”.

He said McClintock had failed to explain what motive Norvill would have had for inventing her claims against Rush.

But Chrysanthou said it was not the court’s role to establish her motivation. “Her own evidence was rife with contradictions, inconsistencies and recent invention,” she said.

“Mr Blackburn [spoke] over and over yesterday [about] Ms Norvill’s motive. What could possibly be her motive to lie. Who cares? That’s not your honour’s job, it’s not our job, to speculate about what is going on in her mind.

“Motive is irrelevant ... people lie. We don’t know why.”

Chrysanthou said Wigney would have to weigh Norvill’s evidence against the testimony of other witnesses including the play’s director, Neil Armfield, and co-stars Robyn Nevin and Helen Buday, who testified during the trial that they had not seen any inappropriate conduct.

She also referred to “a sea of absent witnesses” including a fellow co-star, Helen Thompson, and the Sydney Theatre Company stage manager Georgia Gilbert, to whom, according to Norvill’s testimony, Rush had also behaved inappropriately during the play.

“Imagine Mr Rush behaved like this on a daily basis,” Chrysanthou said.

“How is it possible if Ms Norvill is telling the truth that not one person saw it? [And] she goes even further. He wasn’t just doing it to me, he was doing it to all these other people.”

In her evidence Norvill suggested other cast members had “enabled” Rush’s alleged behaviour, and suggested that a generation gap between cast members may have meant some did not see his behaviour as inappropriate.

But Chrysanthou said the suggestion that “older members of the cast thought it was OK doesn’t make sense”.

She pointed to the evidence of Mark Winter, a cast member of a similar age to Norvill who gave evidence that he had seen Rush make groping motions above her.

“Mr Winter didn’t even register it as an incident,” she said. “He never spoke to Ms Norvill about it, he never spoke to anyone about it. He never even thought about it until three years later.”

Wigney remarked: “He obviously didn’t think much of it.”

Earlier on Thursday the judge said “bad puns” in the Telegraph’s headlines may have undermined Rush’s denials.

“[That] argument would have significantly more force if not for the subeditors,” he said. “They just can’t help themselves with their bad puns. Bad puns is probably putting it in mild terms.”

Wigney said there was “some considerable merit” in Blackburn’s argument that the article had emphasised Rush’s denials.

But, he said, “the problem” were the headlines such as “King Leer” and “Star’s bard behaviour”, which he likened to “very large puffs of smoke suggesting there’s a fire there”.

Rush’s lawyers have argued the articles convey a string of false and defamatory imputations about him, including that he is a “pervert” and a “sexual predator”.

But Blackburn told the court on Thursday that terms such as “pervert” and “sexual predator” were not conveyed in the articles. He likened the term “pervert” to the behaviour of a “Peeping Tom” engaging in “bizarre and disgusting” behaviour.