There was controversy when Cody Rhodes left WWE with WWE having trademarked Rhodes, and not allowing him to use the name. Edge and Christian discussed the reason that WWE was able to do this.
“You can’t copyright someone’s birth name, so that would probably be the reason why…”
It appears that the only reason that WWE was able to do this was because it was never his birth name in the first place, as his actual birth-name was Runnells.
“Christian Cage was mine because I used that name before I was in WWE but shortened it to Christian when I was in WWE. So when I left there was no issue with me calling myself Christian Cage but there obviously would’ve been if I called myself just Christian.”