I doubt it's about patents, since Carmack himself wouldn't be involved if it was. This seems to be a copyright issue, i.e. whether Carmack did a ctrl+c, ctrl+v

I doubt it's about patents, since Carmack himself wouldn't be involved if it was. This seems to be a copyright issue, i.e. whether Carmack did a ctrl+c, ctrl+v on something he didn't own. Alternatively perhaps Zenimax has additional and convincing information about how the works in question was re-implemented. Was it done by Carmack himself, or did a team implement it from his specification?