This will all be hearsay. How will schools know if she said yes or no? Will they take her word for it? What if the accused claims she said yes, but she denies saying yes? Who do you believe? How will they justify whom to believe?
I wouldn't be surprised if they found the accused to be guilty. This is one way California is making it so that college campuses don't have any false-rape allegations. They will only get rape cases.
In theory it would prevent many clear instances of rape from happening, however it will likely lead to a lot of false accusations.
I think the best solution would be to educate girls how to better protect themselves from sexual assault and to better educate men as to why rape is wrong and the moral consequences.