How can police officers tell the difference between someone who is texting while driving, which is illegal in Pennsylvania, or dialing a phone number, which is not?

Usually, they can't. And that has meant few citations issued by local police in connection with the two-year-old texting ban.

Since the law took effect in March 2012, police departments have issued 251 tickets in Allegheny County. Only six of the county's 130 municipalities had 10 or more citations, led by Pittsburgh with 40, according to data provided by the Administrative Office of Pennsylvania Courts (AOPC).

Statewide - excluding Philadelphia, which is not included in the AOPC data - police had issued 2,342 citations as of the end of March, Allegheny was a close second among counties, trailing only Montgomery, where 253 were issued.

"It's a very difficult charge to prove, the way the law is written," said Howard Burton, police chief in Penn Hills, where the force had issued only one texting citation through March 31.

"I think one of the issues is, you can use a handheld device to dial 10 digits and that's not considered texting," said Bryan Kelly, chief of Shaler police, who also had just one citation since the law took effect.

The law imposes a $50 fine for convictions, but court costs add $102.50 to the price of a texting ticket.

When the texting law was debated, a Senate-passed version included a ban on handheld phone use by drivers, but that was stripped out of the final bill.

Forty-three states and the District of Columbia ban texting while driving, but only 12 states plus the district have made handheld cellphone use illegal, according to the Governors Highway Safety Association.

In New York state, which bans handheld cellphone use, police issued about 55,000 texting-while-driving citations last year, more than 20 times the number issued in two years in Pennsylvania.

"They did it right when they started into this, and Pennsylvania didn't," Burton said.

State Rep. Joseph Markosek (D., Allegheny) has introduced legislation to ban handheld phone use by drivers. The bill sits in the Transportation Committee.