Failure to Yield Right Of Way

What is the name of your state? MS

Specifics: 4 Lane Highway(2 lanes each way), East and West Bound Lights were both green. My son was making a left hand turn and got hit by an oncoming vehicle. He had plenty of time to make the turn had the oncoming truck not been speeding. The vehicle my son was driving was a Ford E150 van. The other vehicle was a Chevy S10. The chevy hit the van so hard that the van tipped on it's side and spun 180 degrees. My son made it through the first lane and halfway through the second lane before he was hit. The officer cited him for failure to yield. The van was hit at the back of the second side door(at the rear tire). The other car did not even attempt to get in the other lane. I am not sure what to think about the failure to yield, I was told that if your vehicle was hit more than halfway back(it was) that it was not failure to yield????

What are normal standards in incidents like this?

Also, on the ticket that the officer gave to my son, Where the checkbox for Accident(yes or No) is he has checked no???? What does this mean?????

It will be a week before I can get an accident report. I am not sure if I need to be getting pictures to try and fight the failure to yield and/or any pending lawsuit or what???

Please Help!!!