Prosecutors in Monroe County frequently use “retrograde extrapolation” to prove DUI charges under Section 3802 of Title 75 of the Pennsylvania Statutes. Defense attorney Brian Jordan identifies flaws in custody chains and clinical lab storage (among other issues) to seek to suppress the prosecution’s BAC evidence in his clients’ cases.
Blood alcohol concentration (BAC) readings play a central role in many Pennsylvania DUI cases. Under the Commonwealth’s implied consent law, drivers suspected of driving under the influence are required to provide a BAC sample in most cases, and prosecutors routinely present BAC evidence in court.
But, in many cases, prosecutors must rely on “retrograde extrapolation” to prove a defendant’s BAC at the time of their arrest. This is due to two key factors:
- The police may not take a driver’s BAC until well after the driver’s traffic stop; and,
- A driver’s BAC will be constantly changing (either up or down) from the moment the driver stops drinking.
As a result, even if a driver’s BAC reading is accurate at the time it is taken, it may not be an accurate reflection of the driver’s BAC when they were behind the wheel. Retrograde extrapolation seeks to address this issue, but there are various potential issues with the retrograde extrapolation process as well.
The Science of Retrograde Extrapolation
As a result, if you are facing a DUI charge in Monroe County based on your BAC, addressing the issues inherent in the retrograde extrapolation process could be key to your defense. A defense attorney who is familiar with these issues will be able to examine the prosecution’s analysis of your BAC and determine what defenses you have available. Some examples of issues your defense attorney may be able to raise on your behalf include:
- Alcohol Elimination Rate: Retrograde extrapolation often relies on the average alcohol elimination rate—the rate that the average person’s body processes alcohol in the blood. However, individuals’ alcohol elimination rates can deviate significantly from the average. Since prosecutors must be able to prove your guilt beyond a reasonable doubt, if they cannot prove your alcohol elimination rate, this could be enough to save you from a life-altering DUI conviction.
- Rising BAC: When you stop drinking, your BAC does not stop rising right away. Depending on how much you had to drink, your BAC could continue rising for up to two hours. If your BAC rose after the police pulled you over, your BAC may not have been above the legal limit when you were driving—and this might not be reflected in the prosecution’s retrograde analysis.
- Individual Biological Factors: Gender, body composition, and various other biological factors can impact your alcohol absorption and elimination rates. Even factors like how hydrated you are can play a role in determining your BAC. Here too, if prosecutors do not take all of these factors into account, this could be enough to raise a reasonable doubt about whether your BAC was over the legal limit at the time of your arrest.
- Flawed BAC Reading: Several factors can result in a flawed BAC reading after a DUI arrest in Monroe County. If your BAC reading was flawed, the prosecution’s retrograde extrapolation will necessarily be flawed as well.
- Flawed Retrograde Extrapolation Methodology: Retrograde extrapolation is a complex scientific process. As a result, even if your BAC reading was not flawed, flaws in the retrograde extrapolation process could still lead to an inaccurate assessment of your BAC at the time of your arrest. If prosecutors have conducted a retrograde analysis in your case, your attorney can scrutinize the prosecution’s analysis and determine if there are any issues that you can (and should) raise in court.
Again, these are just examples. An experienced defense attorney may be able to raise various other issues as well. To help ensure that your defense attorney has the opportunity to fully analyze the prosecution’s case against you and develop an informed and comprehensive defense strategy, you should schedule a free initial consultation as soon as possible.
Challenging Section 3802 Breath and Blood Tests
As we mentioned above, along with challenging the prosecution’s retrograde extrapolation of your BAC at the time of your arrest, it may be possible to challenge your BAC reading on several grounds as well. Breath and blood tests can both suffer from various issues, including (but not limited to):
- Failure to provide appropriate instructions prior to testing
- Improper calibration of testing equipment
- Improper administration of the breath or blood test
- “False positive” readings due to medical conditions or other biological factors
- “False positive” readings due to other confounding factors
These are just examples as well. Here too, once you hire an experienced defense attorney to represent you, your attorney will be able to examine the facts of your case to determine what defenses you have available.
Lab Storage and Chain of Custody Flaws
Along with flaws in the testing process, lab storage and chain of custody flaws can also render retrograde extrapolation unreliable—and thus inadmissible in court. Improper storage can lead to contamination and various other issues, while breaks in the chain of custody can raise inherent questions about whether a sample is truly representative of a driver’s condition at the time of his or her traffic stop.
Technical Suppressions in DUI Cases in the Poconos
If the prosecution’s evidence of your BAC is unreliable, it is up to you to prove it. This will involve filing a motion to suppress in your DUI case. While DUI defendants can pursue technical suppressions on various grounds, doing so requires an in-depth understanding of the relevant science as well as the relevant laws and court procedures. This is yet another reason why it is important to have an experienced defense attorney on your side.
Request a Free Initial Consultation with Monroe County DUI Defense Attorney Brian Jordan
Are you facing a DUI in Stroudsburg or the Poconos? If so, Monroe DUI defense attorney Brian Jordan can help. To schedule a free initial consultation as soon as possible, call 570-282-9485 or tell us how we can reach you online now.