Drivers instinctively reduce their speed when they see a police car at the side of the road, fearing that police radar will penetrate deep into their wallets.

But in Pennsylvania, unless that cruiser has a state trooper behind the wheel, radar cannot be in play. Pennsylvania remains the only state that does not allow local police to use radar. Across the state, as one police chief recently said, local officers can carry machine guns but not radar guns.

The prohibition has been in effect for more than 50 years. It is not arbitrary. Lawmakers worried that local police and governments would use radar as a cash cow - setting unfair speed traps to issue speeding citations, especially against people from neighboring communities and other folks just passing through.

That concern can be addressed by requiring regular reports on speeding enforcement on fine collection, which would indicate whether local police are more interested in revenue generation than in public safety.

Meanwhile, Republican Rep. Mario Scavello of Monroe County, a former mayor of Mount Pocono and former county commissioner, has introduced a bill that would lift the prohibition and allow the use of radar at the local level.

Mr. Scavello has noted that in 2011, Pennsylvania had the second highest percentage of speeding fatalities to total fatalities in the nation. On roadways where state police don't patrol and, therefore, radar is not allowed, speeding fatalities were three times greater than on roads where radar is allowed.

Of 1,310 traffic fatalities statewide in 2012, according to PennDot, 534 involved speeding.

Under Mr. Scavello's bill, full-time officers in full-time departments would be able to use radar for speed enforcement. For the first three months, they would be allowed to issue only warnings.

State and local police favor the change. Radar is easier to use and maintain than some non-radar forms of speed monitoring, and it has a good record for accuracy.

It often is a good idea to let other states experiment first with policy and technology. But now that 49 others have embraced radar, the 50th safely can take the plunge.