Elon Musk goes to trial after accusing the Thai cave rescue diver Vernon Unsworth of being "a pedestrian boy."
Musk claimed he was not making a real charge, but a US judge ruled that sued for defamation is strong enough to go to court.
The CEO of Tesla was largely condemned by the comments he made in 2018 about Unsworth, a British diver who played a key role in rescuing 12 boys from a cave in Thailand.
Unsworth told CNN that the Musk offer of a mini-submarine to help children out was "nothing more than a public relations stunt."
"You can hang the submarine where it does wrong," he said.
As a retaliation, Musk wrote an angry Twitter release in which he questioned the role of Unsworth in the # 39; operation and made the unfounded accusation that he was a "pedon".
He followed this two months later in a series of emails to a Buzzfeed journalist, calling Unsworth a "child rapist" who "took a 12-year-old girlfriend."
Musk's lawyers argue that he only affirmed his "opinion," so that defamation law is not applied.
However, Judge Stephen Wilson says that there is enough evidence that Musk was making "objective statements".
"There is nothing about the context in which accusations made statements – in emails to a specific reporter – that could create doubts as to whether the statements of the accused involve objective factual assertions," he wrote.
"In fact, the accused made his statements about the media, whose task is to discover and collect data," he added.
The pre-trial conference will take place on October 7.
It is the last legal problem of Musk, who recently established another lawsuit with the Securities and Exchange Commission for allegedly violating the law of securities with false and deceptive tweets.