The makers of the Oculus Rift virtual reality headset are being sued by game publisher ZeniMax, best known for owning id Software and Bethesda, for allegedly infringing on the company's trademarks and patents for the virtual reality technology.

ZeniMax filed the lawsuit Wednesday in the U.S. District Court for the Northern District of Texas, a few weeks after it sent a letter to both Oculus VR and parent company Facebook alleging ownership of some of the key technology in the Oculus Rift. Defendants include Oculus VR and founder Palmer Luckey.

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In a briefing to press, the company described its basis for the suit:

The suit arises from the defendants’ unlawful exploitation of intellectual property, including trade secrets, copyrighted computer code, and technical know-how relating to virtual reality technology that was developed by ZeniMax after years of research and investment. ZeniMax provided this valuable intellectual property to defendants under a binding Non-Disclosure Agreement that specifies such intellectual property is owned exclusively by ZeniMax and cannot be used, disclosed, or transferred to third parties without ZeniMax’s approval. ZeniMax’s intellectual property has provided the fundamental technology driving the Oculus Rift since its inception. Nevertheless, the defendants refused all requests from ZeniMax for reasonable compensation and continue to use ZeniMax’s intellectual property without authorization.

Oculus VR released a statement in response, saying "The lawsuit filed by ZeniMax has no merit whatsoever. As we have previously said, ZeniMax did not contribute to any Oculus technology. Oculus will defend these claims vigorously."

On May 5, shortly after the first letters were sent to the company, Oculus VR released a statement that said, "There is not a line of ZeniMax code or any of its technology in any Oculus products."

The fight centers around game pioneer John Carmack, who joined Oculus VR as its Chief Technology Officer last August. Carmack remained at id Software, which he co-founded, for some time, but then chose to leave and devote all his time to Oculus VR. ZeniMax claims Oculus technology uses some of its code, a fact Carmack disputes.

No work I have ever done has been patented. Zenimax owns the code that I wrote, but they don't own VR. — John Carmack (@ID_AA_Carmack) May 1, 2014

We've reached out to Oculus VR for new comment on the suit, and will update the story as it develops.