I know, West and Zampella were the main ones though at IW and the team before that, was just referring to them as IW, as thats what most know them as.
Anyway. Yes Activision own the rights to Call of Duty. But when the legal battle first started Activision owned the rights to Call of Duty. But West + Zampella themselves owned the rights to the name 'Modern Warfare' and also owned the rights to any 'Call of Duty' game based after Vietnam.
That is how it stood when West + Zampella took them to court and vice versa. Then W+Z's argument was that bonuses were held back considerably and Acti were looking for a reason to fire them and made it impossible to work there, bodyguards on the doors, searching their files etc.
And Acti's argument was that W+Z broke contract and tried to talk to EA and other potential partners whilst under contract. Not really fussed either way to be honest but anything that stops Activision being able to whore out another franchise is a win for me.