JACKSONVILLE, Fla. -- Police were out in force Wednesday with stepped-up enforcement of a little-known traffic law, and they said failure to comply with it puts officers at risk.

At dozens of locations, the Jacksonville Sheriff's Office is aggressively enforcing the "move over" law, which requires drivers to drop their speed 20 mph below the posted speed limit and to move into a far lane if possible when passing a law enforcement or fire-rescue vehicle with emergency lights on.

The law was enacted in July 2002 in an effort to prevent officers being injured or killed by passing vehicles on the highways. Last year, 15 officers across the country died when they were hit by cars while on duty.

"The majority of people on the road, they would never intend to hurt an officer," JSO Lt. Michael Eason said. "But a lot of officers will tell you that they'd rather go into a dark alley with an armed suspect than work a crash on the interstate because they're more fearful of getting hit by a vehicle."

During the first hour of heightened enforcement Wednesday, police said 60 percent of motorists were not complying with the law. Most people stopped told officers that they didn't know about the law.

Anyone cited would be charged with a moving violation that comes with a $112 fine and three points on their driver's license.