According to
this Wall Street Journal article, John Carmack and Oculus Rift have been put on notice by ZeniMax's legal team.
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Thanks to everyone that sent this one in.
In recent weeks, lawyers for ZeniMax have sent two
letters each to Oculus and Facebook, saying former ZeniMax employee John
Carmack, who joined Oculus last August, improperly took ZeniMax's
intellectual property with him to Oculus, according to documents
reviewed by The Wall Street Journal. That technology, the company
claims, propelled Oculus from a shoestring startup to technology's big
leagues in less than two years.