Facebook CEO Mark Zuckerberg has appeared in court to testify on behalf of his virtual reality company Oculus Rift, which has been accused of stealing the technology from another developer.

Zenimax Media, owner of games studio id Software – known for creating the likes of Quake and Doom – filed a US$2bn (€1.87bn, £1.62bn) lawsuit against Facebook claiming that its early innovations were copied when Palmer Luckey created the Oculus Rift headset.

The lawsuit is centred around games designer John Carmack, who co-founded id and for a short time was working for both id and Oculus before leaving the former completely in November 2013.

Zenimax has accused Carmack of sharing intellectual property with Oculus while at id, later taking the software he was working on with him. Speaking at the trial, Tony Sammi, lawyer for Zenimax called the alleged theft “one of the biggest technology heists ever”.

Speaking at the trial yesterday (17 January), Zuckerberg called the charges “false”, adding that “it’s pretty common when you announce a big deal that people just come out of the woodwork and claim they own some part of the deal.”

During the trial, Zuckerberg also revealed plans to invest around US$3bn (€2.8bn, £2.43bn) in making the Oculus technology better over the next decade. If found guilty, Facebook would be forced to pay US$2bn on top of that sum to compensate Zenimax.

In his testimony, Zuckerberg claimed that Facebook researched Oculus for months and that he was not aware of any theft claims against the company. Zuckerberg also denied that Carmack had unfairly used computer code from his time at id, stating “there is no shared code in what we do”.

“We’re eager to present our case in court,” said an Oculus statement. “Oculus and its founders have invested a wealth of time and money in VR because we believe it can fundamentally transform the way people interact and communicate.

"We’re disappointed that another company is using wasteful litigation to attempt to take credit for technology that it did not have the vision, expertise, or patience to build.”