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The speeding tractor-trailer big rig owned by Wal-Mart Stores Inc. (NYSE: WMT) that collided last month with a limo occupied by comedian Tracy Morgan and some friends was equipped with a collision-avoidance system that failed to function properly, according to a lawsuit filed in New Jersey last week. One person was killed and Morgan and three others were injured in the collision.

The driver of the truck has been charged with death by auto and assault by auto, and a criminal complaint filed in New Jersey also accuses him of not having slept for more than 24 hours before the crash, a violation of state law.

The big rig, manufactured in 2011 by Peterbuilt, a division of PACCAR Inc. (NASDAQ: PCAR), was equipped with a collision-avoidance system that apparently was not functioning properly, and Walmart “knew or should have known that one of the truck’s most important safety features was compromised.” Walmart also knew or should have known that having the truck’s driver commute 750 miles to pick up his truck before working a 14-hour day was unreasonable.

If the charges in the lawsuit are proved to be true, it points to a significant flaw in the new technologies that are being adopted by carmakers: user error. If the systems are not maintained and routinely tested by the vehicle’s owner, there is no assurance that those systems will work.

Federal regulations also govern how many hours a person can drive a truck each day (11) and how many hours that driver can be on duty in a single day (14). The truck’s driver had worked 13.5 hours on the day of the collision, according to federal investigators, and the lawsuit claims that he had spent 11 hours driving from his home in Georgia to New Jersey to go to work. At the time of the crash, the truck was traveling 65 mph in a construction zone where the speed limit had been lowered to 45 mph.

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