SUMMERVILLE — A decibel meter doesn’t look like a weapon. It looks like a personal digital assistant with a dial and a needle.

And, even in the hands of a deputy sheriff, a device that measures noise might not pack much of a wallop.

Dorchester County Council is struggling to pass a law regulating excessive noise, one of those legislative black holes for local governance.

Law after law has been drafted by various governments, with varying success. Charleston, Summerville and Berkeley County are among the towns and counties that have noise laws.

They each wrestle with a few nettlesome problems, such as: Just how much noise is too much, at what time of day and how do you enforce that?

“If it comes down to an officer’s judgment, the court can’t accept that,” Dorchester County Councilman David Chinnis said.

County Council approved a preliminary vote on its law earlier this week, while a draft is still being worked on. So far, the law doesn’t spell out details, such as how high a decibel reading is too high, and under what circumstances.

Readings from a decibel meter are the only evidence deputies or code- enforcement officers usually have to bring to court, and the accuracy routinely is challenged.

Like radar guns, the devices must be calibrated regularly for accuracy if the court is going to accept them at all, and defense attorneys chomp at the bit to prove radar guns wrong.

Decibel meters can cost $100 or more each; calibrating one can cost hundreds each time.

Worried about that recurring cost, Chinnis asked Sheriff L.C. Knight how many officers he has to enforce the law, and Knight replied bluntly, “not enough.”

“Every officer has to have one on patrol,” said council Chairman Larry Hargett said.

That’s not the only problem. The ordinance is cumbersome. The two pages nailing down the regulation carry five more pages of exemptions and rules permitting exceptions.

The law is aimed at curtailing noises, such as from loud cars, motorbikes or music in the densely populated lower county, but it must be enacted for the county as a whole. It’s so broad that, as Chinnis noted, a violation could be cited for a crowing rooster.

A conviction could carry a $100 to $500 fine and 30 days in jail. The county now is revising the ordinance, modeling it after a Berkeley County law that specifies details, such as decibel readings.

A majority of council seems poised to pass it. Make no mistake, Hargett said, loud noise is a problem in the lower county. The two complaints he hears most as a council member are noise and barking dogs.

Reach Bo Petersen at 937-5744, @bopete on Twitter or Bo Petersen Reporting on Facebook.

Science and environment reporter. Author of Washing Our Hands in the Clouds.