Officials with the county sheriff's department, the Maryland State Police and the Hagerstown City Police said they plan to aggressively enforce the law, which carries a $25 penalty.
Mullendore said he expects a flood of tickets over the next three months as drivers get used to the new law.
"It's going to be targeted," he said. "It will be significant over the next three months, without a doubt."
Even without primary enforcement power, Mullendore said deputies have had plenty of opportunity to ticket people without seat belts. In 1996, he said the department issued 5,113 traffic tickets. About 15 percent of those - 752 - were for not wearing seat belts, he said.
The same is true for state troopers, according to spokeswoman Sgt. Laura Lu Herman. Statewide, troopers issued about 52,000 seat belt citations in 1996 - a rate of roughly 1,000 per week, she said.
"We've always focused on enforcement of seat belts - even when it was a secondary offense," she said.
Herman said police zero in on seat belts because of their life-saving potential. During the first half of 1997, 298 people died in traffic accidents in Maryland, she said.
Of those, 199 people were not wearing seat belts, Herman said. Of those, investigating troopers determined that 110 - or 37 percent of the total number of deaths - would have lived if they had worn safety belts.
Washington County officials are particularly interested in the seat belt law because of the rising number of traffic deaths, according to 1st Sgt. Mike Hegedus of the Hagerstown barracks of the state police.
Hegedus said 25 people have died so far this year in traffic accidents in Washington County. That is up sharply from 11 deaths at the same point last year.
Hagerstown City Police Capt. Robert Hart said officers will search for motorists without seat belts as they would any other traffic violation.
"It will become a routine part of traffic enforcement," he said.