A magician never reveals his secrets. Well, not unless a court mandates it.

David Copperfield, 61, is in the midst of a civil jury trial in Las Vegas’s Clark County District Court that began on Friday, following a negligence lawsuit filed against the illusionist by 58-year-old British chef Gavin Cox.

Cox attended one of Copperfield’s shows at the MGM Grand Las Vegas on Nov. 12, 2013. The show concluded with one of the magician’s signature tricks, “Lucky #13.”

Copperfield chose 13 random audience members to participate in the illusion. Cox was one of the 13 — but things quickly went downhill, and Cox claims that he emerged from the trick injured. Copperfield took the stand Wednesday and argued that the trick wasn’t dangerous.

The trick, which Copperfield has performed for at least a decade, is a simple vanishing act. He brings 13 unwitting participants on a platform on stage. Then giant curtains are flung over it, completely obscuring the baker’s dozen of audience members. Copperfield banters for a few minutes before pulling the curtains and revealing the 13 have disappeared.

But the big reveal comes when Copperfield points to the back of the room and tells the audience to turn around. Standing there are the missing participants.

Of course, the participants aren’t magically transported from one place to another.

Cox claimed in his lawsuit that he was injured during the trick, which would force its mechanics to be exposed in the courtroom. Copperfield’s lawyers argued that disclosing how the trick works to the public would financially hurt Copperfield, who is worth about $800 million, according to Forbes.

“It’s not just tricks,” Copperfield said in 2013. “Secrets and lots of hard work go into this.”

The judge disagreed, pointing out that the thousands of people who have already participated in the illusion know how it works. (Copperfield has performed the trick with more than 55,000 different participants without any other incidents, his lawyers said, according to NBC.)

Chris Kenner, the show’s executive producer, explained the trick in court on Tuesday.

After the curtains obscure the participants, flashlight-carrying stagehands guide them off the stage and through dark hidden passageways that wind around various parts of the resort. At one point, the participants exit and then reenter the building. Eventually, they reenter the theater through the back.

Cox said the passageways were filled with dust and debris, as they snaked through parts of the resort that were under construction.

Cox fell during the dash and was taken to a hospital with a dislocated shoulder. He claimed that he later began to suffer chronic pain, and doctors found a lesion on his brain. He said his medical bills totaled more than $400,000, NBC reported.

“There was a duty by the defendants to provide a safe environment to the audience participants,” Benedict Morelli, an attorney for Cox, said in opening statements on Friday.

When questioned about the safety of the trick, Copperfield was slightly cagey — but eventually said that the passageway was safe.

“If somebody participated in the 13 illusion, and they were injured, it’s their fault, not yours, yes or no?” Morelli asked him Wednesday.

“I can’t answer that as a yes-or-no question,” Copperfield responded. “It would depend on what happened. If I did something wrong, it would be my fault.”

Copperfield admitted that construction debris in the passageway could potentially cause injury, “but there wasn’t construction dust in the way.” He said he knows this because he had earlier walked the same path.

MGM, which is also a defendant in the suit, also claimed the passageways were clear.

“Mr. Cox did not slip; he tripped,” Jerry Popovich, an attorney for the resort, told jurors.

The trial is ongoing. Copperfield is expected to continue testifying on Tuesday.

Cox isn’t the only person who has been injured during one of Copperfield’s illusions. One of the magician’s employees was hospitalized for an injury that occurred during an illusion in which Copperfield appears to walk through the blades of a spinning fan, only to turn to smoke. The assistant’s arm broke after it was caught in the fan.

“This is a trick David has done over 3,000 times. This was a freak accident,” Kenner told People at the time. “People are always saying that it’s magic and it isn’t dangerous. This goes to show you that it is.”

This post has been updated. 

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