How Do I Challenge A DUI Blood Test In Chester County, PA?

If you have been charged with a Pennsylvania DUI after submitting to a blood test, you might think that you will be found guilty based on your results. However, blood tests are not infallible even though most people believe that they are. There are several ways to challenge the results of chemical testing of blood.

A good DUI lawyer in Chester County at DiCindio Law understands the various ways to challenge a blood test to potentially get the results dismissed. Here are some ways your criminal defense lawyer might be able to challenge a DUI blood test.

Challenging procedural errors

Multiple errors can occur when blood samples are drawn, stored, and transported. Your attorney will carefully review the circumstances and procedures used to determine whether you might be able to challenge the results based on improper handling, contamination, storage, or when the blood was drawn.

There is a two-hour window after your arrest within which blood samples should be drawn. If your sample was drawn outside of that window, the results might not be reliable. The person who drew your blood must be someone who has the proper certification to do so. If the person who drew your blood was not certified, the test might be inadmissible in the case against you.

A common error that sometimes happens is when the person drawing your blood uses an alcohol-based wipe to sterilize the site of the blood draw. While nurses and phlebotomists commonly sterilize injection sites, doing so when blood is being drawn for a DUI test can contaminate your blood sample and cause the test to show a higher concentration of alcohol in your blood than what it actually was.

Your lawyer can ask for information about how the injection site was sterilized, and you have the legal right to receive information about it during discovery. If an alcohol pad was used to prepare the injection site, or you cannot get an answer from the police officer, you might be able to challenge your blood test results.

Storage is another issue. Your blood sample must be properly stored before it is transported to the forensic lab. If it was stored improperly and allowed to ferment, the results could be unreliable and inadmissible.

The chain of custody is another area to explore for potential blood test challenges. After your blood sample is taken, the police are supposed to document where it is at and whose custody it is in at every step as it makes its way to and from the forensic lab.

If there are holes in the chain of custody, the prosecutor will not be able to admit your blood test into evidence. This is because the prosecutor must show the chain of custody to the court before a blood test result will be admitted.

Laboratory problems

Even if your blood sample was drawn, stored, and transported correctly, problems can still happen once it reaches the forensics lab. Your attorney might ask for maintenance and certification records for the equipment used to analyze the blood sample.

Blood samples are analyzed using gas chromatography/mass spectrometry, which requires the analysts to measure the blood sample against a known ethanol standard.

The vials must be brought to equal room temperature. If the analyst uses a pipette to place the blood sample and the standard into separate vials for testing, it is possible that he or she could inadvertently contaminate the blood sample.

Some labs have high error rates. For example, in 2013, a lab with a history of problems revealed in an audit resulted in 900 defendants in Orange County, California being notified that their blood samples might be inaccurate. Your attorney can carefully review everything. If it appears that an error might have happened in the lab, your blood test results might be tossed out of court.


Defendants have the right to cross-examine all of the witnesses who are called to testify against them in court. However, a good cross-examination requires careful preparation. Your lawyer will question the parties involved about their qualifications and certifications, including the police, phlebotomist or nurse, the lab analyst, and any others who might be called by the prosecution.

Your lawyer may also compare the police officer’s field notes and written report with his or her testimony and challenge any discrepancies.

Some officers write similar things in nearly every report even though each DUI case is different. Police officers also sometimes exaggerate or embellish what happened when they are on the stand to try to help the prosecutor to secure a conviction.

By challenging the officer based on his or her own written notes, reports, and video evidence, your attorney might show significant doubt exists about what actually happened. When there are discrepancies about what actually happened and what is stated in court, juries and judges are unlikely to find the witnesses credible.

If you have been charged with a DUI after submitting to a blood test, you might be able to challenge the results and secure a more favorable outcome to your case. In some cases, if a blood test is deemed to be inadmissible, the prosecutor might not have enough evidence to prove the case against you and be forced to dismiss it. In others, an inadmissible blood test might result in a plea offer to a lesser offense.

Contact Our DUI Law Firm in West Chester, PA

If you are facing criminal charges and need legal help, contact the West Chester, PA DUI lawyers at DiCindioLaw, LLC to schedule a free initial consultation.

DiCindio Law, LLC

29 S Walnut St
West Chester, PA 19382
(610) 430-3535

***This blog article is made available by the law firm publisher for educational purposes and to provide general information, not to provide specific legal advice. By reading, you understand that there is no attorney client relationship between you and the publisher. The above listed information does not include the entire crimes code, annotations, amendments or any recent changes that may be relevant. The information provided is for informational purposes only and may not reflect the most current legal developments. These materials are not intended, and should not be taken, as legal advice on any particular set of facts or circumstances. Please contact DiCindio Law, LLC for a consultation and to discuss what law is relevant to your case. ***