Originally posted by: hiten mitsurugi
Byakugen can pretty much do everything that Sharingan can and more. Byakugen has better insight abilities (and no that doesn't mean seeing through objects). That's the ability to foresee things before it happens. So if they simply wanted to copy jutsus they easily could, it's just that they don't train byakugen in that manner. Neji gave us a clear indication of this when he used byakugen on Hinata during thier fight. When Neji told her to give up and she said that she wouldn't give up because it's her ninja way. Neji read her thought and said that she totally believed in what she said. He did the same thing to Naruto, when Naruto stated that he would be hokage during their fight.
this is the most incorrect thing i've heard.

How can Hiashi beat itachi when he can't even stare at Itachi? Simple, because byakugen can see 359 degrees. That means that he can fight even with his back turned to him. Just a couple of touches from Hiashi and no more chakra. That means no sharingan, no water clones, no mange, no nothing but taijutsu.
but that's the thing. you cannot fight with your back turned, or in any other way, as well as looking directly at them. and since you bring up 'couple of touches from hiashi and no more chakra.' well, ONE look from itachi and death.