Board Thread:Naruto Discussions/@comment-29857886-20160904193151/@comment-25093611-20160906191546

^not sure how they would stop a genjutsu before it is casted :/

for all we know genjutsu can look like ordinary ninjutsu but the byakugan allows direct look into the chakra flow, that means that genjutsu would be stopped almost immediately after it effects the victim, at least this makes the most sense imo :)