oculusMaryland video game publisher ZeniMax Media has engaged Sard Verbinnen & Co as it mounts a legal and PR challenge to virtual reality company Oculus VR, which was acquired by Facebook for $2B in March.

ZeniMax launched its public salvo on May 1, claiming legal ownership of intellectual property used to develop Oculus' Rift product. ZeniMax went public after it said talks between the two companies fell through and said technology developed by ZeniMax staffer John Carmack, now with Oculus, is the property of ZeniMax.

Sard Verbinnen managing directors Andrew Cole in New York and Paul Kranhold in San Francisco are advising ZeniMax.

Oculus responded May 6 with a statement that it is "disappointed but not surprised" by the ZeniMax move, adding that "we will prove that all of its claims are false." In a point-by-point rebuttal, it said Carmack did not take any intellectual property from ZeniMax, claiming that the exec left the company because it stopped working on virtual reality gaming.

The Redner Group works PR for Oculus.

"No work I have ever done has been patented," Carmack said via Twitter on May 1. "Zenimax owns the code that I wrote, but they don't own VR. Oculus uses zero lines of code that I wrote while under contract to Zenimax."