The Infowars founder has repeatedly held discussions on his web shows in which the massacre has been described as a hoax. Grieving relatives of those killed have been called actors.
Now, Mr Jones is being sued by the families of eight victims and an FBI agent who was one of the first on the scene.
They say they have been subject to harassment and death threats from the 45-year-old’s followers as a result of the theories promoted on his shows.
And they claim that Jones peddles the bogus stories as an essential part of his business model – which sees Infowars advertise products including survivalist gear, gun paraphernalia and dietary supplements to its listeners.
A Connecticut judge ruled on Wednesday that he must give evidence in the case.
Josh Koskoff, an attorney representing the families, said: “From the beginning, we have said that Jones knowingly peddled false and malicious narratives in order to make money at the expense of the Sandy Hook families’ grief, safety and security. Today’s ruling moves us one step closer to proving this.”
Mark Barden, whose son Daniel was killed during the atrocity, added: “It is far beyond time that he be held accountable for the pain his false narratives have caused so many.”
Twenty children, aged just six and seven, and six members of staff were shot dead at Sandy Hook Elementary School in Connecticut in 2012 by a killer who then shot himself.
Mr Jones has not yet commented on the news of the deposition.