Car accident and how to fight it?

ok i got in a car accident... i was changing lanes in between two cars. i was in the lane for 6 seconds and the car in front of me makes a sudden turn. He completes his turn and i start giving gas. The car behind me hits me in the back. the guy comes out screaming and screams at a Asian person that barely know how to speak English. the Asian says after 10 mins it was my fault. They call the police and i get a ticket for unsafe lane change. But the thing i dont get is the car in front of me had so much time to make his lane change and i just think that the car behind me wasint paying attention. i was told i cant fight the accident because im already declared at fault and i can only fight the ticket is this true?Car accident and how to fight it?
I am obviously only getting your side of the story, but usually the one that rear ends some one is at fault. I don't know where you are, but in most states you are at fault because you received the violation. If the violation is thrown out so is your implied guilt!