Blood

A motorist's blood alcohol concentration (BAC) may be measured taking a sample of blood from the motorist. This is usually achieved by withdrawing blood through the cubital vein located just below the bicep. This test is typically performed by a phlebotomist using a needle. Once a blood sample is taken, it will be sent to an approved clinical laboratory for chemical testing. The Pennsylvania Department of Health periodically publishes a list of approved laboratories in The Pennsylvania Bulletin. A blood test is the most reliable method of chemical testing. A BAC test measures the percent weight of alcohol in a measured volume of an individual's blood. Per the Pennsylvania Superior Court, taking a direct sample of blood from a DUI suspect is highly reliable to the degree that the results rise above the level of opinion or conjecture and constitutes medical fact.1

Vehicle code section 1547(j) requires hospitals, physicians, technicians and nurses to withdraw blood at the request of a police officer. By law, hospitals and their employees are immune from civil liability for withdrawing a blood sample from the DUI suspect.

There are two types of chemical analysis performed on the blood sample of a motorist: whole blood analysis and serum analysis.

Blood serum is that which remains after the cells and fibrin, the blood's clotting agent, are separated from the plasma. Since serum is less dense than is whole blood, the weight per volume of alcohol in serum will exceed the weight per volume of alcohol in whole blood. Therefore, in order to obtain a whole blood BAC from a blood serum BAC, an acceptable conversion factor is required to convert the serum BAC to a whole blood BAC.2

Pennsylvania courts have accepted 1.1 to 1.35 conversion rations for serum to whole blood conversions. Consequently, a serum analysis of blood will give a range of potential BAC's for an individual. For instance, a laboratory technician may testify that the DUI suspect's BAC was between 0.1275% and 0.1039% based on the whole blood conversion. Because of this, serum testing is an unpopular method in Pennsylvania. It is more practical and accurate for the prosecution to use a whole blood analysis.

Contact my office if you feel your blood test was performed incorrectly or the results are inaccurate. My office may be able to help. There may be ways to contest the blood test result in your DUI case, such as:

  • Site contamination: use of alcoholic swabs will result in inaccurate BAC reading
  • Varying hematocrit levels of the individual
  • Failure to add preservatives to the blood sample
  • Blood sample became clotted resulting in an inaccurate BAC reading
  • Failure to comply with Department of Health regulations
  • Failure to produce evidence that laboratory was an approved testing facility as stated in The Pennsylvania Bulletin.



1  See Commonwealth v. Sullivan, 581 A.2d 956, 958 (Pa.Super. 1990); Commonwealth v. Krovontka, 558 A.2d 865, 867 (Pa.Super. 1989).
2  Timothy P. Wile & Marc A. Werlinsky, West’s Pennsylvania Practice: Pennsylvania Driving Under the Influence Volume 10, 780 §20.21 (2008-2009 ed. 2008) citing Comonwealth v. Kohlie, 811 A.2d 1010, 1013 (Pa.Super. 2002); Commonwealth v. Michuck, 686 A.2d 403, 406 (Pa.Super. 1996)