San Francisco: Elon Musk's social media platform formerly known as Twitter has sued the state of California over a law requiring social media companies to publish their policies for removing offending material such as hate speech, misinformation and harassment.

The first-of-its-kind legislation was signed into law a year ago by California Gov. Gavin Newsom. In a lawsuit filed Friday against state Attorney General Robert Bonta, X Corp. challenges the "constitutionality and legal validity" of the law, saying it violates the First Amendment.

The California law requires social media platforms to post their content moderation policies — which they already do — and twice a year submit a report to the state on how they address hate speech, racism, misinformation, foreign political interference and other issues.

The law, "compels companies to engage in speech against their will, impermissibly interferes with the constitutionally-protected editorial judgments of companies such as X Corp." and has pressures companies to remove or demonetize "constitutionally-protected speech," says the lawsuit, filed in federal court in California.

Since taking over Twitter in October 2022, Musk has upended the platform's content moderation system, laying off workers responsible for weeding out problematic content and reinstating accounts banned for engaging in hate speech, promoting Nazi and white nationalist material and harassing users.

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Musk also disbanded a key advisory group, the Trust and Safety Council, made up of dozens of independent civil, human rights and other organizations. The company formed the council in 2016 to address hate speech, harassment, child exploitation, suicide, self-harm and other problems on the platform. He has referred to himself as a "free speech absolutist" — though the billionaire has at times proven sensitive about critical speech directed at him or his companies. Last year, he suspended the accounts of several journalists who covered his takeover of Twitter.

The law's author, Democratic Assemblyman Jesse Gabriel, said it is a "a pure transparency measure that simply requires companies to be upfront about if and how they are moderating content. It in no way requires any specific content moderation policies – which is why it passed with strong, bipartisan support."

"If Twitter has nothing to hide, then they should have no objection to this bill," he added.

The attorney general's office said it will review the complaint and respond in court.

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Representatives for X did not immediately respond to messages for comment on Friday. (AP)