On Wednesday, lawyers representing Elon Musk asked a federal judge to dismiss a defamation lawsuit brought by a British cave explorer whom Musk called a "pedo guy" on Twitter. The motion to dismiss, filed in US District Court in California's Central District, argues that Twitter is simply a "website famous for invective and hyperbole," and no one who read Musk's claims took them seriously.

Tangled tweets

The dispute began in July, when Musk began tweeting about using a team of SpaceX engineers to find a way to rescue 12 boys who were trapped in a cave in Thailand as monsoon waters flooded the cave. The team's solution was to develop a child-sized submarine that could keep the children safe as experienced divers guided it through the long and dangerous passage out of the cave.

But several days later, a team of experienced divers and cave explorers were able to rescue all of the children without Musk's help. A Thai official later said that Musk's solution "was not practical for this mission."

Vernon Unsworth, a British cave explorer who played a key role in the operation to extract the boys from the cave, subsequently said in a CNN interview that Musk's submarine was too rigid to take the narrow corners in the cave and had "absolutely no chance of working." Unsworth added that Musk could "stick his submarine where it hurts."

Musk responded by calling Unsworth a "pedo guy" on Twitter. In response to questioning tweets, the CEO didn't walk back his claim and instead wrote: "Bet ya a signed dollar it's true." Musk eventually deleted his tweets, but days later he responded to a Buzzfeed News email reiterating his claims and including several new and equally unsubstantiated claims about Unsworth. Musk wrote that his email was "off the record," but Buzzfeed never agreed to such terms and published the email anyway.

Musk had told Buzzfeed, "I fucking hope he sues me," which Unsworth did in August.

Serious or not?

Now Musk's lawyers are hoping to dismiss the lawsuit, arguing that the general public reading Musk's tweets "knew from the outset" that the insulting remarks "were not intended to be statements of fact."

"While many [Buzzfeed] readers criticized Musk for lodging what they understood to be groundless accusations (and criticized Unsworth for disparaging Musk and his team's efforts to help), not a single reader seemed to construe Musk's statements literally," the motion claims.

Musk's lawyers argue that his tweets are protected under the First Amendment. They also repeatedly use the nature of Twitter as an example of why Musk's tweets should not be taken seriously, calling the site "a turbulent internet forum" and arguing that "reasonable readers discount internet speech" in accordance with the "low barrier to speaking online."

"The motion," Musk's lawyers wrote on Wednesday, "boils down to a single question: Accepting Unsworth's well-pleaded allegations as true, would a reasonable reader believe that Musk's statements were supported by objective facts or instead were 'nonactionable opinion'?"

In an email to Ars on Thursday, Unsworth's lead counsel, L. Lin Wood, rejected Musk's attorneys' characterization of the situation. Wood cited the 1990 US Supreme Court decision in Milkovich v. Lorain Journal, in which the court decided that not everything that might be labeled as opinion is exempt from libel laws.

“Furthermore, I entirely reject Mr. Musk’s frivolous contention that all statements published on Twitter or other social media are protected speech," Wood wrote. "I am confident the trial court will likewise reject this fanciful position which if adopted, would effectively prevent an individual from seeking redress for any and all false and defamatory attacks on reputation published on the Internet.”