User blog comment:Fimber/We don't know whether Morgause was sentenced to death or not.../@comment-70.79.44.61-20120605073631/@comment-5102537-20120607103525

Good question, I've been wondering about that too. Not to mention that he must have known about Vivienne's powers anyway since his relationship with her was before Arthur was born and therefore no one had a reason to hide the magic. So if he knew about Vivienne's powers - and there is no reason why he shouldn't have known about her magic - he also should have known that Morgana has magical powers. Vivienne, Morgause ... so why not Morgana?

When Morgana helped Alvarr to escape, I was under the impression that Uther knew it was Morgana or at least suspected her. Sadly, we won't get an answer to it all.

On the other hand, maybe Vivienne didn't have any powers and M and M inherited theirs from their grandmother or grandfather.

If Uther had sentenced Vivienne to death in case she had magical powers, it would have been a good reason for Morgana to hate Uther, at least it would have been comprehensible why she hated him so much. But I prefer to believe that he didn't.