There are specific procedures for blood draws in Pennsylvania. In addition to these pre and post procedures, laboratories within the Commonwealth must test whole blood as opposed to blood serum.

Our law firm defends a number of DUI (drunk driving) cases in Pennsylvania involving blood evidence. As most of my readers already understand, the legal Blood Alcohol Content (Concentration) Limit (BAC) in Pennsylvania, and all jurisdictions including New Jersey, is .08. While the prosecution doesn’t  need to establish a specific BAC concentration to convict an individual of drunk driving in Pennsylvania (General Impairment DUI – See Section 3802(a), it will need this evidence to prosecute an individual for more serious DUI offenses under the DUI statute (See Title 75 § 3802(b) and (c)).


How is BAC calculated in Pennsylvania? 

There are 2 generally accepted ways in which the prosecution (District Attorney) can establish a specific BAC level—a breathalyzer or a blood draw. I’ve written previous articles on breath test analysisand Henry’s Law and encourage you to read the article, watch the video, and visit my free download section on this topic which is discussed in my free book—5 Ways to Fight & Win Your Pennsylvania DUI. While breath testing is much more convenient and much less intrusive, blood provides a much more specific BAC level because it typically does not require any type of conversion calculation to arrive at a BAC level. It’s important to realize, however, that there are specific procedures for blood draws in Pennsylvania. In addition to these pre and post procedures (non-alcoholic cleansing solution and storage temperature), laboratories within the Commonwealth must test whole blood as opposed to blood serum.


Blood Serum vs. Whole Blood –  Conversion

Blood serum is that which remains after cells and fibrin, the bloods clotting agent, are separated from the plasma. Serum is less dense than whole blood and therefore the weight per volume of alcohol in serum will exceed the weight per volume of alcohol in whole blood. Given this difference, the lab must use an acceptable conversion factor to convert serum BAC to whole blood BAC.


The prosecution (district attorney) can’t convict a defendant of drunk driving in Pennsylvania under DUI subsections of the statute (3802) which specifically include a BAC level within the elements of the offense utilizing solely blood serum analysis. If the prosecution intends to introduce blood serum it must not only utilize a conversion factor but inform the fact finder (judge or jury) that a chemical analysis was performed on the serum as opposed to the whole blood.

Blood evidence is far superior to a breath sample for DUI prosecutions. As stated in previous articles, breath testing is based on various assumptions and constants. Breath samples are converted into BAC results to determine a person’s level of impairment. More and more law enforcement agencies are not, however, using breath tests because of the questions surrounding the reliability of those scientific assumptions.

While a blood test provides stronger scientific evidence of impairment it is much less convenient then a breath test. Blood tests obviously require a medically trained individual unlike breath tests which simply require a police officer to use a device in an appropriate manner. While someone should have some type of qualification to administer blood tests the law does not require this individual to be a doctor, nurse, or any type of licensed person. There is no general rule for qualifications and the law only requires that the person taking this sample be acting in accordance with his or her job description.

Further, the law in Pennsylvania does not even require that blood be drawn at an approved medical facility such as a hospital or clinic but it only requires that an approved clinical laboratory perform the chemical analysis of the sample taken. While some may argue that a blood test is a medical procedure you should understand that Pennsylvania does not require either a doctor or a nurse to order its administration. The law only requires that a police officer make the request and the police officer doesn’t even need to be present while the sample is taken.

After the sample is taken a laboratory and a trained scientist approved by the Pennsylvania Department of Health must perform the analysis. Pennsylvania publishes a list of approved laboratories each year and also the minimum list of qualifications for scientist working in the facility. Approved laboratory equipment, approved procedures, and qualified scientists are the minimal threshold for the admissibility for the blood test. The fact that the prosecution can meet this minimal requirement does not prohibit the defense from challenging the reliability of the tests results.

For more information, visit my free download section