In Forensic Human Factors Analysis for Fatigue Accident Reconstruction, fatigue expert witness Dennis Wylie writes:
There is no breath analyzer or blood test that can reveal the presence of a critical level of fatigue in an accident-involved driver. However, a forensic driver fatigue expert can often conclude to a reasonable degree of scientific certainty whether fatigue was a cause of the accident, by doing a human factors accident reconstruction involving two important steps:
1. a forensic human factors analysis of the driver’s work-rest history leading up to the accident, and 2. a forensic human factors analysis of each particular aspect of the driver’s performance that may have been a cause of the accident.