1. DUI Offense Washington D.C. | Minor Collision Followed by Delayed Breath Test and Revised BAC Estimate
The incident occurred in a crowded commercial parking area in Washington D.C. where the defendant lightly tapped a parked vehicle while reversing at low speed.
Officers responded to the scene and initiated a DUI investigation pursuant to District traffic laws that authorize chemical testing after a collision.
Approximately 50 minutes after the vehicle contact, the responding officer conducted a breath analysis that measured the defendant’s blood alcohol concentration at 0.062%.
Shift in the Government’s Position on Driving Time BAC
During the initial charging phase, the government focused on the measured 0.062% BAC but soon faced questions about whether that value could reliably demonstrate impairment at the time of driving.
Prosecutors then adopted a retrograde extrapolation model to estimate the defendant’s earlier BAC level.
They argued that, based on the defendant’s admission of consuming a small amount of homemade fruit based alcohol and general metabolic assumptions, the defendant’s BAC at the time of driving should be calculated at 0.051%.
This figure exceeded the 0.05% prima facie impairment threshold recognized under D.C. traffic enforcement standards, which permit a presumption of impairment when the BAC surpasses 0.05%.
Because the estimated value exceeded the statutory threshold by only a very small margin, the calculation became the central point of dispute.
Legal Consequences of the Revised Estimate
The prosecution argued that even a narrow exceedance above 0.05% was sufficient to support a DUI offense under D.C. law, asserting that the defendant’s driving behavior and the parking lot contact were consistent with impairment.
The defendant therefore faced continued exposure to criminal penalties based on a number that exceeded the threshold by only a few thousandths of a percentage point.
This raised important questions regarding the accuracy and reliability of the government's assumptions and whether such a marginal difference could satisfy the Constitution’s requirement of proof beyond a reasonable doubt.
2. DUI Offense Washington D.C. | Defense Strategy Targeting Scientific Reliability and Evidentiary Sufficiency
The DUI offense attorney structured the defense around undermining the foundational assumptions behind the government’s extrapolation and demonstrating that uncertainty within the model rendered the estimated BAC scientifically unreliable.
Uncertainty in Retrograde Extrapolation Variables
The defense emphasized that retrograde extrapolation requires precise information regarding the amount of alcohol consumed, the alcohol concentration of the beverage, the timing of consumption, and the defendant’s individualized absorption and elimination rates.
In this case, none of these variables had been verified.
The prosecution relied solely on the defendant’s approximate description of drinking from a small cup containing homemade fruit based alcohol, but no laboratory analysis confirmed the drink’s alcohol content.
Expert review showed that even small adjustments—such as calculating the consumed volume at 70 milliliters rather than 80 milliliters—could push the estimated driving time BAC below the 0.05% threshold.
The defense further explained that homemade beverages vary widely in alcohol concentration, making them poor candidates for precise toxicology modeling.
In addition, the government applied a generic elimination rate rather than determining the defendant’s actual metabolic characteristics.
Taken together, the uncertainties produced a broad range of potential BAC values at the time of driving, many of which fell below the level required to support a DUI offense.
Lack of Corroborating Behavioral Evidence
The defense also highlighted the absence of meaningful observational evidence of impairment.
The defendant stood, spoke, and followed instructions without difficulty. No slurred speech, erratic behavior, or dangerous driving maneuvers were observed.
Even the minor collision in the parking area was consistent with non impairment explanations such as tight parking spaces and limited visibility.
Under D.C. law, behavioral indicators are particularly important when the government’s BAC evidence does not clearly exceed statutory thresholds.
Because the extrapolated BAC figure was already subject to scientific doubt, the minimal behavioral evidence further undermined the prosecution’s case.
3. DUI Offense Washington D.C. | Impact on Accompanying Traffic Charge
The defendant was also charged with negligent driving due to the contact with the parked vehicle. Under D.C. Code § 50-2201.04, negligence offenses may be enhanced when impairment is present.
The prosecution attempted to use the estimated BAC to support both charges simultaneously.
Failure of the Government’s Theory After BAC Evidence Collapsed
Once the court expressed concerns about the reliability of the extrapolation model, the government struggled to sustain the related negligence charge.
Without credible evidence of impairment, the incident amounted to a minor parking lot contact with no aggravating factors.
The driver of the parked vehicle also declined to pursue further action. As a result, the accompanying charge lacked independent evidentiary support and could not move forward.
4. DUI Offense Washington D.C. | Court Rejects Extrapolation and Issues Acquittal
After hearing expert testimony, cross examination, and legal argument, the court concluded that the government failed to prove impairment or a statutory BAC violation at the time of driving beyond a reasonable doubt.
Court’s Findings on Scientific and Legal Deficiencies
The court determined that the prosecution’s extrapolation depended on speculative assumptions regarding alcohol quantity, beverage strength, and metabolic rates, none of which were grounded in objective evidence.
Because reasonable variations in those inputs could produce BAC results below the 0.05% prima facie impairment threshold, the court held that the government had not met its burden.
The court also noted the absence of strong behavioral signs of impairment and found that the minimal exceedance above 0.05% was insufficient to establish criminal liability.
Accordingly, the court acquitted the defendant of all DUI charges and dismissed the related negligence count.
The ruling demonstrated the District’s commitment to strict evidentiary standards and reinforced that criminal convictions cannot rest on uncertain scientific models or assumptions.
05 Dec, 2025
