Elon Musk has been summoned to an emergency court hearing on Thursday over the $1m prizes he has been awarding registered voters in swing states.
The Tesla and X chief executive has been ordered by a judge in Philadelphia, Pennsylvania to address a civil case by the city's top prosecutor to stop Mr Musk and his political action committee, America PAC, from giving the cash away.
The suit accuses Mr Musk of operating an illegal lottery and trying to influence voters in next week's presidential election between Kamala Harris and Donald Trump.
Mr Musk and his PAC are backing Mr Trump, the Republican nominee.
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The controversial billionaire promised to give $1m (£767,000) each day to resgistered voters in swing states who have signed his online free speech and gun rights petition.
The first $1m was awarded to a man named John Dreher during a campaign event in Pennsylvania on 19 October.
Mr Musk is the world's richest person and is worth $274bn (£210bn), according to Forbes, so the approximate $17m (£13m) he's vowed to give away is a tiny fraction of his wealth.
The 53-year-old had donated $75m (£58m) to American PAC in the period up to mid-October.
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Documents filed by Philadelphia's district attorney Larry Krasner also revealed that the lawsuit against Mr Musk had "triggered an avalanche of [social media] posts from Musk's followers," many of whom "made antisemitic attacks on Krasner".
The attorney asked for enhanced security for the hearing, which was originally scheduled for Friday, after users on X had published Mr Krasner's home address.
America PAC is one of several major political action committees in the US.
Such groups can raise and spend unlimited amounts of money in support of political candidates, on the condition that they do not coordinate with their campaigns or give money to them.
Mr Trump has said he will give Mr Musk a government job if he becomes president again.
(c) Sky News 2024: US election: Elon Musk summoned to court over $1m giveaways to registered voters
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