In California, for example, police are barred from using unmarked cars in traffic enforcement, and the state's highway patrol undercover officers who use unmarked cars for surveillance in drug and auto-theft investigations are discouraged from making traffic stops.
"It's just common sense," said Houston. "If the vehicle is not clearly marked, the motorists wondering, 'Is that a cop?' When an individual comes out of an unmarked car or with no uniform, it just creates too much confusion."
Some city county law enforcement agencies have also banned unmarked cars for their traffic divisions and forbid their deputies from hiding while trying to catch speeders. Some departments' policies were prompted by the rare but real problem of police imposters.
In York County, S.C., for example, motorists have twice reported seeing "blue-lighted bandits" in the last year. These were men who had equipped their cars with flashing blue lights- which can be bought by civilians for as little as $29 a light- and tried to stop women driving alone.
In neighboring Lexington County, S.C. sheriff's deputies arrested a 21-year-old-man for impersonating a police officer. Several drivers told police they had been pulled over by a man driving an unmarked car with a dash- mounted blue light. The man walked up to the drivers and pulled a pistol, identifying himself as an officer. He told the drivers they could avoid a traffic ticket by giving him $10.
In Lexington County, Sheriff James Metts had long ago begun to instruct his officers that if they tried to stop a car operated by a woman who is alone, they should follow her until she reaches a safe place- as long as she does not try to speed off. It is a policy followed by state police agencies around the nation, both by departments that use unmarked cars, as well as those agencies that do not.
In North Carolina and Florida, for example, where unmarked cars are used in traffic enforcement, troopers are warned to be patient with motorists who may be uncertain they are officers.
And in Columbia, S.C., city police officers are allowed to use unmarked cars to remain undetected while using radar to catch speeders, but the department requires that a marked unit stop the offender and make the arrest.
Following the incident involved Beckwith, state legislators rushed to try to pass legislation banning the use of all unmarked cars by any law enforcement agency, state or local, in any traffic stop. Some officers call that overreaction and contend only the public will be harmed. If unmarked cars are banned from making traffic stops, for example, then what should a police supervisor or detective, who routinely drives unmarked cars, do when they spot a drunken driver weaving down the road? Isn't it the officer's legal responsibility to stop the driver before someone gets hurt?
"I think the risk to the public posed by dangerous drivers is certainly greater than the remote possibility of being stopped by a police imposter," said Metts, who fears any police that takes away an officer's discretion.
"It all boils down to reasonable individuals who have been trained properly. An officer to have the right to use common sense and discretion," Metts said.
Geoff Alpert, a criminal justice professor at University of South Carolina and a national authority on police management says there is a use for unmarked cars in surveillance and undercover work, but not for traffic enforcement.
"The downshide is that you don't know they're police, you don't know how to respond, and the police get upset if you don't stop," Alpert said. "The point of traffic enforcement is to keep the roads safe and get people to slow down. You can easily do that in marked cars."
But some agencies put the burden for a successful traffic stop on the officer, not the car.
In Indiana, state police use unmarked Mustangs and Camaros that are equipped with darkly tinted windows to nap speeders on stretches of highways notorious for high- speed traffic problems. The department only allows their use during the day.