http://www.bloodyelbow.com/2016/5/1...or-vs-floyd-mayweather-without-ufc-permission
3.5 During the Term, ZUFFA shall have the exclusive right to promote all of Fighter's bouts and Fighter shall not participate in or render his services as a professional fighter or in any other capacity to any other mixed martial art, martial art, boxing, professional wrestling, or any other fighting competition or exhibition, except as otherwise expressly permitted by this...
Conor McGregor can indeed legally book a Boxing match without Zuffas permission (proof inside)
3.5 During the Term, ZUFFA shall have the exclusive right to promote all of Fighter's bouts and Fighter shall not participate in or render his services as a professional fighter or in any other capacity to any other mixed martial art, martial art, boxing, professional wrestling, or any other fighting competition or exhibition, except as otherwise expressly permitted by this...
Conor McGregor can indeed legally book a Boxing match without Zuffas permission (proof inside)
