Honestly, I do feel bad for him in this scene. He can't admit guilt or innocence! A tricky position indeed, and one with lots of possibilities behind it.
-Hilary

Mowbray's in a really sticky situation, it seems. He did the Kings bidding, but he can't just say that, it would get the King in trouble. He can't say what he did was wrong, because that would imply that the King is wrong. Not Allowed! What's he supposed to do? Of course he's counting on the King to have his back... which Richard doesn't.
Erin Kay Schulz

I guess one of the reasons this part has been confusing and ambiguous for a lot of us is because of all the changing of minds. It's hard to follow what the people are feeling at all times. Mowbray's feelings and loyalties make him a very confusing character.

-Renee Ward

I've already stated this once but there is also that whole fight with Bolingbroke. At first he gets incredibly defensive and angry, accepting Bolingbrokes challenge and throwing down his own gage. But after Richard says like three words to him, Mowbray's all like, "Ok. I'm cool with just letting it slide."
*Tina

This is a little ambiguous. I don't know that a viewer of the player ever really gets to know just what his sworn duty is. In one sense, it is to the king and the body politic, which means, if he did kill Gloucester, then he did his sworn duty. But, he wouldn't want to admit that. There was also a sworn duty to keep Gloucester safe for Richard, which clearly didn't happen. Which one he is referring to is hard to say. It could be that the killing was supposed to be done quietly, with no links to Richard but that he was found out. Lots of possibles. Bradley