SOMERSET, Pa. -

People who told police they were not that drunk while driving may have been right in one southwestern Pennsylvania county.

Somerset County District Attorney Lisa Lazzari-Strasiser told the (Somerset) Daily American that a local hospital has been testing drivers' blood serum, not whole blood, when doing the tests.

As a result, the blood-alcohol content has been overestimated by up to 15 percent.

That's important because the blood-alcohol level is used to determine whether someone is legally drunk and, in some cases, whether they deserve more severe punishment.

Tests using blood serum can be used as evidence, but only if a calculation is done to convert the percentage of alcohol found as though it were taken from a whole blood sample.

The DA said her office failed to perform those calculations and is reviewing some cases.