Other driver fighting citation in accident. What should i take to the appeal hearing?

My girlfriend was in a car accident. she was pulling right out of a alley and was struck by a truck coming up over the hill. The cop said he had to be doing at least 80 in a 25 mph zone based on the skid marks running for 65 feet. The other driver is fighting the citation issued for the wreck and his company is denying fault right now. What can I do at his appeal (take with me) to help ensure his citation is not overturned. there was a witness statement given to police stating they saw it as his fault, plus i have pics of the speed limit signs posted and of some skid marks. Any advice on how to keep him from winning this case and his insurance being able to claim him not at fault. both my son and girlfriend were both injured in the accident as well.