A deadly incident takes the issue of sleepy drivers to the criminal courts.

You probably remember hearing about the Chinatown bus that crashed on Interstate 95 on the way back from the Mohegan Sun Casino in Connecticut last year, killing 15 passengers and injuring many more.

The tragic incident has taken so-called “drowsy driving” into the courtroom. According to a story from The New York Times, law enforcement officials are increasingly pushing to hold drivers criminally liable when their sleep deprivation results in fatal automobile accidents.

But how can you define “drowsiness” when it comes to driving? As the Times notes, “A blood-alcohol test can show whether a driver was drunk. Skid marks may betray a speeder. And cellphone records will reveal whether someone was texting right before a crash. But drowsiness is a personal and often fleeting state of mind that leaves no permanent record.”

However, the danger of driving while drowsy is clearly very real and can have permanent consequences. In a report from ABC News, Dr. Meir Kryger of the Yale Sleep Medicine Clinic said, “Sleep is such a powerful drive. If you need it, the brain will say ‘Sleep’ and that can be an incredibly dangerous situation.”

The lack of a standard for measuring drowsiness has been a primary hitch in the trial of the aforementioned bus driver, Ophadell Williams, who was – according to the prosecution – so sleep-deprived that the effects of his fatigue could be equated to driving under the influence of alcohol. For two months following the crash, in which the bus veered off of the road and flipped on its side before its roof was nearly sliced off by a metal signpost, prosecutors tried to prove their case against Williams, who was charged with manslaughter and criminally negligent homicide.

A sleep expert, as reported by the Times, testified that Williams had slept an insufficient amount in the 72 hours prior to the crash, having only napped two to three hours on the bus while passengers gambled in the casino. The article continues, “The shift from polite chiding to prosecution follows successful efforts to criminalize other dangerous driving habits, like speeding, drinking alcohol and using cellphones.”

Have you driven while drowsy? Is there any conceivable way of implementing a standard to keep people as tired as Ophadell Williams from behind the wheel? Weigh in here.