434 Alexandre de Moraes, a Brazilian Supreme Court justice, on Thursday in Brasília. Justice Moraes has sweeping powers to police content on Brazil’s internet. Credit... Leer en español As Brazil grappled with a flood of online disinformation around its 2022 presidential election, the nation’s Supreme Court made an unusual and fateful decision: It gave one justice sweeping powers to order social networks to take down content he believed threatened democracy. That justice, Alexandre de Moraes, has since carried out an aggressive campaign to clean up his country’s internet, forcing social networks to pull down thousands of posts, often giving them a deadline of just hours to comply. It has been one of the most comprehensive — and, in some ways, most effective — efforts to combat the scourge of internet falsehoods. When his online crackdown helped stifle far-right efforts to overturn Brazil’s election, academics and commentators wondered whether the nation had found a possible solution to one of the most vexing problems of modern democracy. Then, on Friday, Justice Moraes blocked the social network X across Brazil because its owner, Elon Musk, had ignored his court orders to remove accounts and then closed X’s office in Brazil. As part of the blackout order, the judge said internet users who tried to circumvent his measure in order to keep using X could be fined nearly $9,000 a day, or more than what the average Brazilian makes a year. It was the judge’s boldest measure yet, and it left even many of his defenders worried that Brazil’s experiment had gone too far. “I was someone who was very on his side,” said David Nemer, a Brazilian-born media professor who has studied his nation’s approach to disinformation at the Berkman Klein Center for Internet & Society at Harvard University. We are having trouble retrieving the article content. Please enable JavaScript in your browser settings. Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times. Thank you for your patience while we verify access.