We like to think drunk drivers are the exception rather than the rule. But, at 1:30 a.m., on a major Interstate? Who knows?

The odds played out with tragic consequences last week when a Massachusetts State Police sergeant was killed while stopping traffic on an exit ramp for construction work.

Sgt. Douglas Weddleton had parked his cruiser on an I-95 ramp at 1:30 a.m. with his lights flashing when a drunk driver tried to maneuver around his car.

While dealing with that drunk driver, another one slammed into the first car, pinning the trooper beneath it and dragging him across three lanes of the highway.

Anthony Perry, who had been watching the NBA Finals at a Rhode Island bar, was later charged with negligent motor vehicle homicide and operating under the influence of alcohol.

Sgt. Weddleton left a wife and four sons, ranging in age from 14 to 26.

According to the National Law Enforcement Officers Memorial Fund, 154 U.S. police officers were killed after being struck by vehicles between 2000 and 2009. Such accidents are the number one killer of police officers nationwide, according to the Maine State Police.

Which is one of the reasons that a variety of states, including Maine, have passed "move over laws," which require drivers to slow down and, if possible, move into the opposite lane.

Maine's law was passed in 2001 and applies to any emergency vehicle using an emergency light, which includes fire trucks and ambulances. The law was amended in 2007 to include tow trucks.

The minimum fine under the statue is $311.

Even though the law was passed nearly ten years ago, it was not in effect when many of today's drivers learned to drive, so it is spottily observed.

Still, it's a common-sense law meant to save lives.