At fault? - AZ

My brother was in a traffic accident and was given a ticket for "failure to yield". He was in the left turn lane at an intersection when the light turned yellow. He watched the approaching cars and everyone was slowing down so he proceeded to turn. While turning he was hit in the rear end by a truck that had sped up to make the light. I was under the impression that if your body is not in the intersection at the time the light turns yellow, that you have to make the stop and can be ticketed for running the light if you don't. The other person was not cited for anything. Am I wrong in believing that this accident was the other person's fault? Should my brother fight this ticket in court, he does have a witness, someone approaching the light at the same time the accident occured? Please help, any information will be greatly appreciated!!

Was the car approaching from behind your bro (travelled in same lane also turning left) or approaching from the right (going through green light and bro didn't get out of the way fast enough)? The first scenario is worth fighting; the second is harder to win. Good luck. Don't forget, have your witnesses there!!

Thank you for your reply! The other car was coming towards him from the other side of the street and he didn't get out of the way fast enough.