By Alexandra Berzon

YouTube went off-line in a huge swathe of Brazil over the weekend after a major internet service provider complied with a court ruling to shut down the popular video-sharing site until a controversial sex video is permanently removed.

The controversy began when renown model and MTV host Daniela Cicarelli sued the Google-owned Web site after a video of her apparently having sex with Merrill Lynch banker Renato Malzoni became the most-viewed YouTube offering in Brazil.

Google tried to take the video down, but it kept reappearing on the user-generated site. A Brazilian judge on Thursday ordered the country’s internet service providers to block YouTube until it permanently removed the video.

By Friday, Brazil Telecom, the country’s second-largest fixed-line telephone operator, had begun blocking access to YouTube across a large stretch of Brazil, including the capital, Brasilia. A spokesperson from Brazil Telecom told the AP that the decision to deny access to YouTube was a direct response to the judge’s orders, which will be automatically reviewed by a panel.

The incident has called into question the basic ability of legal systems to control internet content. And on the frontlines are the internet service providers.

“Internet service providers are increasingly the enforcers of Internet laws,” said John Palfrey, a HarvardLawSchool professor and executive director of the school’s BerkmanCenter for Internet and Society. “The broad trend of Internet regulation is toward a blurring of the public and the private. In order to get the enforcement done, states need the help of private intermediaries.”

In a statement Friday, YouTube spokesperson Jaime Schopflin was unclear about how YouTube would proceed.

“YouTube is under the jurisdiction of the U.S. legal system. However, we reach a global audience and strive to provide a community where people from around the world can share videos in a safe and lawful manner,” said Scholpflin.

Meanwhile, the steamy beach video was viewed by curious gawkers on numerous Web sites around the world. In Brazil, bloggers complained vociferously about state-sponsored censorship. “It seems that Brazilian Justice is not prepared for Web 2.0,” said a “Blog Do Dez” blogger. Other YouTube diehards found crafty ways to get around the blackout, such as accessing the site directly by typing in its numerical IP address.

Contact the writer: aberzon@redherring.com