A British man is suing American magician David Copperfield claiming he was badly injured while participating in a 2013 Las Vegas show.

Gavin Cox, who was at the performance for his birthday, was selected to take part in an illusion that appears to make 13 audience members vanish. The 58-year-old from Kent claims he suffered lasting brain damage and a shoulder injury after falling on debris in a construction site during the trick.

Mr Copperfield’s lawyers lost pretrial bids to close proceedings to the public to avoid giving away performance secrets. The magician’s friend and executive producer, Chris Kenner, revealed to jurors how the illusion was performed.

Stagehands ushered participants through dark curtains, down secret passageways and through backstage areas before leading them back into the theatre, where they would “reappear” during the performance finale, Mr Kenner said.

“Is that route an obstacle course?” asked Benedict Morelli, representing Gavin Cox, who claims injuries sustained in the fall have have cost him more than $400,000 (£280,000) in medical care.

Mr Kenner, whose company Backstage Employment and Referral Inc is also a defendant in the case, denied the suggestion.

“At no time are they told what they’re going to do before they start this illusion,” Mr Morelli asked Mr Kenner. “They’re told as they’re running the route, correct?”

Mr Kenner answered yes, but declined to say it was dangerous to lead people along a dark route over changing floor surfaces including linoleum, cement and carpet.

The lawyer said before Mr Cox fell, the group were led through an alley coated with what Mr Morelli called construction dust.

MGM Grand hotel attorney Jerry Popovich told the jury of eight women and four men last week that 10 minutes before Mr Cox fell, Mr Copperfield safely walked through that same area as part of another illusion that did not involve audience participation.

He said Mr Copperfield would have alerted stagehands if he noticed any problems along the way. The court case continues.

Associated Press contributed to this report