IP-2024-000061 - [2025] EWHC 1936 (IPEC)

Battlekart had one witness of fact, the defendants two. Sébastien Millecam is the founder and a director of Battlekart. He is Belgian, has good English and did not seek to rely on an interpreter. One of the items of prior art relied on by the defendants was a prior disclosure by Battlekart itself about which he principally gave evidence.

Mr Millecam was criticised for being occasionally inaccurate in his witness statement and for attempting to suppress information about Battlekart’s prior disclosure from the Battlekart website. There may be something in this but I think that so far as it mattered Mr Millecam gave honest answers according to the best of his knowledge and recollection. He was a good witness.

The defendants’ first fact witness was Mr Maguire, the fourth defendant, who was only asked a few questions.

Another item of prior disclosure in issue was the ‘Live-Action RC Mario Kart’. This was a game created by three individuals who at the relevant time were students at the Massachusetts Institute of Technology (MIT). For a project which formed part of their course on software development, they created live version of the Mario Kart game using remote-controlled toy karts. One of the students was Nathaniel Rodman who provided a witness statement for the defendants. He was not cross-examined.

Battlekart’s expert witness was Warren Viant, Senior Lecturer and Deputy Head of School at the School of Computer Science at the University of Hull. The defendants’ expert was Gilray Densham. Mr Densham had a career in lighting for TV shows and then became the founder and former CEO of the CAST Group of Companies which develops software and lighting systems for live productions. The CAST Group manufactures and supplies, among other things, an infrared location system for use in amusement parks and immersive entertainments.

Mr Viant seemed in cross-examination to have retained a shaky grasp of the concept of common general knowledge (CGK). In re-examination he was asked to confirm a paragraph in his first report that identifies CGK, which he did. The concept is in fact better stated in a later paragraph in the same report, but even if he had confirmed that paragraph, the wording of which indicates that it was drafted by lawyers, the confirmation would not necessarily establish that Mr Viant had taken the concept of CGK fully on board.

There was an issue regarding how much Mr Viant knows about the sort of XR with which the Patent is concerned and the techniques used in such systems. Mr Viant has experience of XR systems such as plane cockpit simulators and has worked on projects such as XR software used to train radiation therapists. These are not the same as XR in the amusement and entertainment industries. Mr Densham expressed astonishment that Mr Viant did not know about matters which Mr Densham regarded as both important and clearly part of the CGK.

Possibly in an attempt to plug this gap, in examination-in-chief Mr Viant was asked about his students and what they had gone on to do after graduation. He said that the vast majority have gone into the fields of computer graphics, computer games and XR. Battlekart submitted that he will have talked to his former students and must have become more widely informed about XR. That may or may not be right, but it would not be evidence of Mr Viant’s first-hand knowledge. Without knowing in more detail what was said by whom to Mr Viant, it says nothing about his second-hand knowledge either.

A difficulty for both sides was a consequence of the parties each having a single expert. Keeping the number experts to the minimum was as it should be in this court but meant that it was going to be difficult to find an individual who has a sufficient background in each of the relevant disciplines. This should have been raised at the case management conference.

There was a project Mr Densham worked on that was given particular attention. It is a tracking system which locates moving items, such as the positions of actors on a stage or vehicles on a track. The system’s software coordinates these locations with lighting, sound, drones, lasers or other matters to generate appropriate effects at the right time and place for the production. The system is called ‘BlackTrax’. It was launched by the CAST Group in February 2012, around 3 years before the priority date. Mr Densham said that by 2013 BlackTrax was one of the industry standards as a tool for production and entertainment design. It has been widely used in live entertainment. Since before the priority date there have been similar systems available off the shelf. Mr Densham identified two others: Autopilot II and ZacTrack. He gave technical details about BlackTrax and about those two.

The system marketed by the defendants which is alleged to infringe the Patent is called ‘Chaos Karts’. It uses BlackTrax which plays a major role in making Chaos Karts work, providing it with a tracking system and software to coordinate it with a projection system and actuator control of the karts. Mr Densham knew this before giving his evidence. Battlekart submitted that this was highly significant hindsight which undermined the credibility of Mr Densham’s evidence on obviousness. I am not sure that it does. Mr Densham of course knows a great deal about the capabilities and potential applications of BlackTrax. It seems to me that if Battlekart’s point on hindsight were to be made good, it would have been necessary to pinpoint one or more aspects of the suitability of BlackTrax for a system such as that claimed in the Patent which could not have been predicted by Mr Densham without first knowing that BlackTrax has been successfully used in Chaos Karts. It would also have been necessary to investigate with Mr Densham the significance of any such matter regarding his views on inventive step. Neither was done.

Mr Densham was criticised for not engaging with the technical issues in the case and instead for the most part saying that they would be taken care of by BlackTrax. As I will discuss below, an important part of Battlekart’s case on CGK was that BlackTrax and similar tracking systems were not part of the CGK. If that is correct, some of Mr Densham’s evidence loses force. If it is not correct, Mr Densham gave technical details about these tracking systems. Assuming here that one or more of the three tracking systems was part of the CGK and that it would have occurred to the skilled team to use any of them, Mr Densham was entitled to assert, based on his technical explanation of how they work, that any of them would have made the implementation of a system as claimed in the Patent straightforward. He did make that assertion and of course it was open to Battlekart to challenge it, which was done. But it is not correct to say that Mr Densham failed to address the technical issues.