One challenge to winning a truck driver fatigue case is proving that the driver was indeed tired and not fit to drive at the time of the accident, and that his sleepiness was the main cause of the accident. There are several way to do this:
The driver may admit to being tired at the time of the accident - either to witnesses at the scene or to the police during the initial questioning.
The driver may appear fatigued to police or witnesses, even if he does not admit that this is the reason for the accident. He might have bloodshot eyes. He might not be fully alert.
A review of the driver's road log could add insight into whether or not he was fit to drive at the time of the accident. The Motor Carrier Safety Regulations permit only a certain number of hours of active duty in a certain time span before the driver should be off the road for safety reasons.
If you think that the truck driver that caused your car accident was suffering from fatigue, you should call a knowledgeable and specialized lawyer immediately. Proving fatigue often means connecting and analyzing a wide range of sources - including the driver's log, the truck's maintenance records, the driver's history, and the witness reports. Only a lawyer will be able to accurately tell you if your case holds enough water for recovery.