Brazil judge wrangling with Elon Musk has long battled social media

In recent years, de Moraes has slapped fines and bans on social-media companies and ordered police to investigate—and even arrest—some of the country’s most powerful conservative bloggers, businessmen and politicians over what he deemed offensive online posts.

Now the court’s order to block a swath of X accounts has sparked fresh debate, with critics on the right, including many legal experts, saying de Moraes has gone too far. They argue his crusade to clean up the internet in the name of safeguarding democracy is arbitrary and repressive, and that the biggest risk to democracy in Brazil could be the Supreme Court.

Musk appears to think so. On Monday, he said de Moraes had given X two hours to suspend a series of high-profile accounts from the platform, formerly known as Twitter, which the tech magnate acquired in 2022.

“We were being given demands to suspend sitting members of the parliament and major journalists, and moreover we could not tell them that this was at the behest of Alexandre de Moraes and we had to pretend that it was due to our rules of service," said Musk during a podcast.

“That was the final straw and we said no," he said, describing the order in another post as “the most draconian demands of any country on Earth."

Musk has called for de Moraes’s removal and has goaded him online in recent days, referring to the judge as “Brazil’s Darth Vader" and likening his powers to those of a “brutal dictator."

Supporters of former right-wing President Jair Bolsonaro, who gave Musk a medal during his visit in 2022 to announce plans to install satellites over the Amazon rainforest, have reveled in Musk’s defiance, declaring him a “hero," as the dividing lines in Brazil’s culture wars deepen.

“There are eerie parallels with the United States," said Christopher Garman, managing director for the Americas at Eurasia Group, a political-risk consulting firm, pointing to fears among both Democrats and Republicans ahead of the U.S. presidential election. “Each side is fully convinced that the other is a threat to democracy."

Brazil’s Supreme Court, which hasn’t made the original court order public, didn’t respond to requests for comment, either on behalf of the court or de Moraes himself.

But de Moraes, who said he has received a stream of death threats since Bolsonaro called him “scum" at a major rally in 2021, has shown no signs of backing down. “We Supreme Court judges are not cowards," the 55-year-old justice said recently.

Despite also clashing with de Moraes in the past, members of President Luiz Inácio Lula da Silva’s leftist Workers’ Party jumped to his defense over recent days, calling Musk’s failure to comply with the court order an attack on Brazilian sovereignty.

“Social media is not a no man’s land!" de Moraes wrote in bold caps in a follow-up decision Sunday to include Musk in his sweeping investigation into disinformation campaigns online.

He also ordered an investigation into Musk for the crimes of obstruction of justice, being a member of a criminal organization and incitement—crimes that can carry jail sentences of more than 10 years in Brazil, according to a court document.

Brazil’s face-off with Musk comes as the world’s largest democracies, from the U.S. to India, battle to regulate fast-growing social-media platforms, grappling with fundamental questions such as whether freedom of expression should also give citizens the right to lie.

But the stakes in Latin America’s most-populous nation are particularly high, said João Brant, the government’s secretary for digital policies, who has said his country could serve as a laboratory to test out policies that could be adopted elsewhere.

In Brazil, a nation of more than 200 million people—the world’s fourth-largest democracy—the private messaging app WhatsApp is now considered the principal source of information, according to a 2019 government poll. Some 79% of Brazilians said they got their news via the app, compared with 50% from television and 8% from newspapers.

“This means that a large part of public debate is not happening in the open," said Brant. “This diminishes the ability of the Brazilian justice system to act and makes combating disinformation in the country more difficult."

The Supreme Court has resorted to blanket bans of accounts of social-media platforms instead, making the most of the expansive powers afforded to the court by Brazil’s constitution.

At 64,488 words, Brazil’s constitution is one of the most detailed and lengthiest in the world, giving the Supreme Court powers to intervene on wide-ranging issues as the gatekeepers of constitutional law.

The court’s 11 justices, along with their armies of attorneys, have already ruled on close to 26,000 cases this year alone.

Brazil has had a particularly rocky relationship with democracy, emerging from a 21-year military dictatorship in 1985, under which Bolsonaro himself served as an army captain.

Recent probes by de Moraes into Bolsonaro and his role in the storming of Congress by his supporters in January 2023 have concluded that the conservative leader not only plotted a military takeover of the country before the 2022 presidential elections but also encouraged his supporters to unseat da Silva from office.

Bolsonaro has denied wrongdoing in all of the cases, saying he is the victim of a witch hunt by the left and the country’s left-leaning top judges.

In his secondary role as temporary head of Brazil’s electoral court, de Moraes led a trial last year that resulted in Bolsonaro’s ban from political office until 2030. In February this year, he ordered police to seize Bolsonaro’s passport, and his supporters fear that de Moraes could soon order the former president’s arrest.

Not long ago, many Brazilians weren’t familiar with individual Supreme Court justices. But the Car Wash corruption case that embroiled the country’s top politicians and in 2018 landed da Silva in jail for 19 months, plunged the court into the middle of Brazilian politics. The court was forced to make the final decision on key cases, including da Silva’s eventual release from prison that paved the way for his election as president.

Bolsonaro’s own rise and his open attacks on the Supreme Court have also prompted the court to award itself greater powers to combat his right-wing supporters, largely with the support of the political left.

In 2019, the court’s lead justice at the time, Dias Toffoli, gave de Moraes permission to open a so-called “fake news inquiry" to probe attacks on the court—traditionally a role only played by prosecutors.

“Moraes suddenly became the investigator, the accuser, the victim and the judge all at the same time. Brazil tolerated this because a consensus had formed that Bolsonaro was a threat to democracy and so people ended up accepting it," said Leonardo Barreto, a Brasília-based political scientist.

But it is a dangerous precedent, he said. “What happens when this type of arbitrary justice, these illegalities are also directed at the very people who supported it?"

Write to Samantha Pearson at samantha.pearson@wsj.com