By Cherri Gregg

PHILADELPHIA (CBS) — The Pennsylvania State Police is temporarily requiring blood tests for DUI stops on state highways, including along the Schuylkill Expressway and I-95.

This change resulted from a ruling in Dauphin County, Pa., where a judge held that breathalyzers are unreliable (see related story).

Meanwhile, Philadelphia police say they will continue to use breathalyzers in DUI stops, so blood tests will only be required by state police on highways.  But Philadelphia attorney Joe Kelly, who specializes in drunk-driving cases, says defense lawyers are gearing up to challenge the use of breathalyzers on city streets as well.

“According to Justin McShane, the lawyer who handled the case out in Dauphin County, and the experts I spoke to, the machines don’t even work properly. Somebody could have a .06 and it could read a .10,” he tells KYW Newsradio.

And Kelly says that could be the difference between guilt or acquittal on a DUI charge.

Dauphin County prosecutors are expected to appeal the decision questioning breath tests, but if the ruling goes to the Pennsylvania Supreme Court and is upheld, Kelly says it would apply across the commonwealth.

“It could affect thousands of cases statewide,” he says.  “Thousands of cases.”

Kelly says of the 10,000 DUI cases in Philadelphia each year, roughly 70 percent are based in part on breathalyzer tests.