After a serious crash, existing laws already empower prosecutors in most states to present evidence to a jury that a driver's sleep deprivation amounted to reckless conduct. It's no shocking intrusion of privacy to examine the log books of a commercial driver who's caused a fatality or even, if it's relevant to the negligence issue, the cellphone and credit-card records of a private driver in the same situation.
But as The Times reports, many "traffic-safety advocates, researchers and lawyers" would like to go further. Taking drunken driving as the model, some hope to criminalize "dangerous driving habits" like drowsy driving even if a driver has caused no accident and broken no other traffic laws. And libertarians and defense lawyers are right to object.
To begin with, under the principle of the rule of law, persons exposed to criminal penalty deserve fair notice of what conduct is lawful and what is not. In the case of drunken driving, we pretend at least to objectivity in the form of breath analysis and a rule of thumb of so many drinks per hour. Yet there's no objective or even pseudo-objective test for drowsiness. Will cops be empowered to pull over the stone-sober driver at the D.U.I. checkpoint whose eyelids look too droopy, or watch the convenience store for drivers who seem too eager for a double coffee at 3 a.m.?
Highway fatalities have been declining for decades, and we've already forfeited enough of our individual liberty to uniformed officers at checkpoints. Quoted in The Times, the New York lawmaker who sponsored one failed bill against drowsy driving seemed mystified that "There was a concern that government again was encroaching into people's day-to-day lives." Yes, there was. And that concern is valid.