MARYLAND DUI • BLOOD / SERUM TESTING • EXPERT CHALLENGES
Scientific Challenges to Blood-Draw DUI Cases in Maryland
Many DUI “blood test” numbers begin as hospital serum/plasma results and are later converted into a whole-blood BAC estimate. That conversion can depend on assumptions, specimen handling, and uncertainty. This guide explains what those issues mean and how they can matter under Maryland’s expert reliability standard.
1) Serum/Plasma Results Often Require Interpretation
Hospital ethanol results are frequently reported from serum or plasma. A forensic “BAC” number may be produced by converting that value to a whole-blood estimate. The key point: conversion is not just arithmetic— it relies on assumptions about specimen type and how alcohol distributes.
2) Conversion Factors Are Often Reported as Ranges
Research comparing plasma/serum and whole blood ethanol concentrations frequently reports conversion ratios in ranges. In litigation, when the State presents a single number, it can be important to ask: which ratio was chosen, why that ratio, and how sensitive the final output is to that choice.
3) Method + Specimen Type Can Affect “Apples-to-Apples” Comparisons
Some cases involve hospital enzymatic testing of serum/plasma and forensic gas chromatography testing of whole blood. Those are different specimen types and different analytical methods. A careful defense asks whether the comparison being made is scientifically sound for the question the court is being asked to answer.
4) Uncertainty and Assumptions Can Matter at Trial
Timing, absorption/elimination assumptions, specimen handling, and measurement variability can all influence confidence in a calculated result. When a number is presented as precise, it’s fair to test whether the method, assumptions, and limits were clearly stated—and whether the approach is reliable for the specific case.
Illustration: Small Ratio Shifts Can Change the Output
This simplified example shows why ratio choice matters. It’s not presented as a medical conclusion—only as an illustration that changing a conversion input can change the final calculated value.
Illustrative conversion (serum → whole blood)
- Serum: 193 mg/dL
- Ratio 1.13: ~0.170 g/100 mL (BAC)
- Ratio 1.19: ~0.162 g/100 mL (BAC)
Context for ratio ranges: PubMed reference →
Scientific Support (High-Authority Sources)
- NIH/PMC: Plasma/Serum/Whole Blood ethanol comparisons + storage variables
- PubMed: Winek & Carfagna (plasma/serum/whole blood comparisons)
- PubMed: Hospital serum alcohol vs forensic whole-blood testing methods
- NIST OSAC (.gov): Guidelines for alcohol calculations in forensic toxicology
- Rochkind v. Stevenson: Maryland expert reliability standard (summary)
Want a focused review of your blood/serum testing issues?
If conversion assumptions, specimen type, timing, or expert methodology are central to the State’s theory, start with a focused review and a plan.
E-FILED; Montgomery County District Court - Rockville
Docket: 3/26/2025 6:04 PM; Submission: 3/26/2025 6:04 PM
Envelope: 20535367records, e.g., forensic toxicology, the specific calculations performed, or the handling of
biological samples under the conditions present in this case. The expert’s experience
lacks sufficient peer reviewed publication, or experience in the specific methods used in
this case. The expert lacks sufficient experience in calculating BAC with the provided
known and unknown variables present in this case.
- Lack of Reliable Principles and Methods: The calculations performed by Hayley A.
Mulder, PhD, particularly the conversion of serum alcohol concentration to BAC using a
range of 1.13 to 1.19 for the serum/plasma to blood ratio, are based on assumptions and
generalizations that may not be applicable to the David R Wright. - The State has failed to establish the reliability of the methods used, specifically: The
scientific literature supporting the chosen serum/plasma to blood ratio range and its
applicability to individual variations. The specific protocols used for handling and storing
the biological sample, and the potential impact of any deviations from those protocols.
The lack of individual analysis of the serum/plasma to blood ratio of the defendent. The
lack of accounting for retrograde extrapolation. The inherent variability in the
measurement of serum alcohol concentration and the impact of that variability on the
final BAC calculation have not been adequately addressed. The expert cannot explain the
standard deviations associated with the result. 3. Insufficient Factual Basis: The expert's
opinion relies on incomplete information, notably the lack of a known drinking history
for the David R Wright. The expert has not provided a sufficient factual basis for their
opinion regarding the level of impairment associated with the calculated BAC, failing to
account for individual factors such as tolerance or metabolic differences. 4. Lack of
Relevance and Helpfulness: The expert's testimony, based on a range of potential BACvalues, is not sufficiently precise to assist the trier of fact in determining the David R
Wright's level of impairment at the time of the incident. The expert has not adequately
accounted for the time between the incident, and the taking of the blood sample, and
therefore the BAC at the time of the sample, does not directly relate to the BAC at the
time of the incident. The wide range of possible BAC values, makes the experts
testimony unhelpful, and potentially misleading. - Maryland Rule 5-702 and Rochkind v. Stevenson: As established in Rochkind v.
Stevenson, Maryland has adopted the Daubert standard for admissibility of expert
testimony. The proposed testimony of Hayley A. Mulder, PhD fails to meet the
requirements of reliability and relevance under Maryland Rule 5-702, as interpreted by
Rochkind v. Stevenson.
CONCLUSION
WHEREFORE, For the foregoing reasons, the David R Wright respectfully requests that
this Honorable Court grant this Motion and exclude the expert testimony of Hayley A. Mulder,
PhD. The admission of such testimony would violate Maryland Rule 5-702 and the principles
established in Rochkind v. Stevenson, and would deprive the David R Wright of a fair trial.
Respectfully submitted,
/s/ Christopher Moschkin
Christopher.G¡.Moschkin?.Esq¡
CPF#: 1812120031
Christopher.G¡.Moschkin?.Esq¡.LLC
3100 Verona Court
Silver Spring, MD 20906
(240) 992-4733Chris@rockville-law.com
Attorney for Defendant David R Wright
CERTIFICATE OF SERVICE
I HEREBY CERTIFY that on the 26th day of March 2025, a copy of the foregoing copy
of the Motion.to.Exclude.Expert.Testiony was delivered via MDEC eFile and Serve to the
Office of the State’s Attorney for Montgomery County.
/s/ Christopher Moschkin______
Christopher G. Moschkin
CPF #: 1812120031
PRIMARY-SOURCE + PEER-REVIEWED REFERENCES
Scientific Support for DUI Blood Testing
This page discusses real-world DUI blood/serum testing issues (conversion ratios, uncertainty, and assumptions). Below are high-authority NIH / PubMed / NIST sources that support the underlying scientific concepts.
Plasma/Serum vs Whole Blood: Systematic Differences
Demonstrates that plasma/serum ethanol concentrations can read higher than whole blood and discusses why handling/storage and collection methods matter when interpreting results.
Reported Serum-to-Whole-Blood Ratios (Literature)
A classic reference comparing plasma, serum, and whole blood ethanol concentrations—useful for explaining why “conversion factors” are assumptions, not magic.
Hospital Serum vs Forensic Whole Blood (Method Differences)
Compares hospital serum testing methods with forensic whole-blood gas chromatography—supporting the point that lab method + specimen type can change interpretation.
Alcohol Calculations, Assumptions & Uncertainty
A forensic-science guideline addressing alcohol calculations, specimen types, population variance, and why extrapolation/conversion requires stated assumptions (and careful limits).
Want the “science” applied to your case?
If blood/serum results or testing assumptions are driving the State’s theory, start with a focused review and a defense plan.