Korean DUI Suspect Acquited of Drunk Driving: Korean Supreme Court Required Empirical Proof of Blood Alcohol Concentration Formula Calculation Inputs

The Supreme Court of Korea recently clarified the evidentiary threshold for proving Korean drunk driving when no direct blood or breath alcohol test is available. The ruling emphasizes that, in Korean DUI cases, the Widmark formula (an estimation method used to calculate blood alcohol concentration (BAC)) must only be applied where the underlying facts, including alcohol consumption and timing, are established through proof and not mere conjecture. The punishment for DUIs in Korea is strict and, in some cases, can lead to a jail sentence and deportation for expats. For an additional post on Korea’s DUI Law, please see: Korean DUI Law and Implications for Foreigners Residing in Korea.

Case Background

This landmark Korean DUI decision is referred to in the local Korean press as the “Gwangju Maserati hit-and-run.” The case underscores that aggressive proactive counsel can lead to a not guilty verdict in DUI cases in Korea.

1. On September 24, 2024, at approximately 3:10 A.M., the Defendant drove a Maserati at approximately 128 km/hr. – more than double the posted 50 km/hr. speed limit. The vehicle collided with a motorcycle, causing severe permanent injuries.
2. The Defendant fled the scene of the accident and contacted an acquaintance to assist him in evading the authorities and securing a new mobile phone.
3. The Defendant was indicted under the Korea’s Act on the Aggravated Punishment, etc. of Specific Crimes (Hit-and-Run Resulting in Death) and related Korean statutes.

Korean Trial and High Court Holdings

The Korean trial court found the Defendant guilty on all counts, including drunk driving and aiding and abetting the escape of a criminal. The court sentenced the Defendant to ten years in prison. On appeal, the Gwangju High Court partially reversed the lower court’s holding. The Korean court determined that the prosecution had failed to strictly prove the elements necessary to apply the Widmark formula for BAC estimation.

The Widmark formula estimates blood alcohol concentration (BAC) and is calculated as:

BAC=(A/(W*r))−(β*H)cap B cap A cap C equals open paren A / open paren W * r close paren close paren minus open paren beta * H close paren𝐵𝐴𝐶=(A/(W*𝑟))−(𝛽*H). The basics for calculation require the total grams of alcohol consumed (A), the person’s body weight in kilograms (W), the Widmark factor ‘r’ (approximately 0.680.680.68 for men and 0.550.550.55 for women), the elimination constant βbeta𝛽 (typically 0.150.150.15 g/L/hour), and the hours over which alcohol was consumed (H). 

Investigators had relied heavily on CCTV footage to estimate the Defendant’s BAC before the accident. The High Court held that such footage could not accurately establish either the quantity of alcohol consumed or the time of consumption, which, as can be seen above, are essential inputs for the Widmark calculation.

The High Court opined that:

“Determining the amount of alcohol consumed based on CCTV footage alone is speculative and cannot be considered strict proof. Even if the estimate is accepted, the Widmark formula must be applied under conditions most favorable to the defendant, including the lowest absorption rate and earliest possible commencement of alcohol metabolism. On this basis, it cannot be concluded that [Defendant’s] BAC exceeded the statutory threshold of 0.03%.”

This appellate court found Defendant not guilty of drunk driving and of aiding and abetting a criminal’s escape, reducing his sentence to seven years and six months in prison for the hit-and-run offense.

Korean Supreme Court Decision (2025Do9963)

On October 16, 2025, the Korean Supreme Court’s Second Criminal Division (Presiding Justice Eom Sang-pil) affirmed the appellate court’s judgment and dismissed both the prosecution’s and defendant’s appeals.

The Korean Supreme Court held:

“The lower court’s findings do not deviate from the rules of logic and experience nor exceed the boundaries of the principle of free evaluation of evidence. The appellate judgment correctly applied the legal principles governing the establishment of drunk driving under the Road Traffic Act and aiding and abetting the escape of a criminal.”

The Supreme Court of Korea thus confirmed the acquittal on the disputed charges and upheld the seven-year and six-month prison sentence imposed for the remaining hit-and-run offenses.

Legal Significance for DUI Cases in Korea

This ruling carries significant implications for future Korean criminal cases involving indirect BAC estimation. The Korean Supreme Court reaffirmed that the Widmark formula cannot substitute for empirical testing absent substantial evidence of the Widmark formula parameter inputs.

In the majority of criminal defense cases that will go to trial, it is essential to have criminal defense lawyers on your team who have worked as Korean court judges, have significant experience defending foreigners in Korean courts, and have also defended foreigners before the Korean Immigration Services and the Korean Administrative Court.

Charged with a crime in Korea? Schedule a call with a Korean Criminal Defense Lawyer at: Schedule a Call with an Attorney. For more articles on Korean Criminal Law, please see our Korean Defense Law Archives.

by Sean Hayes

Sean Hayes is the first non-Korean attorney to have worked for the Korean court system (Constitutional Court of Korea) and one of the first non-Koreans to be a regular member of a Korean law faculty. Sean is ranked, for Korea, as a Top Attorney by AsiaLaw, and IPG Legal is consistently ranked Top Dispute Resolution Law Firm for our litigation and arbitration services.

If you would like a consultation with Sean Hayes from IPG Legal, please schedule a call at:  Schedule a Call with Attorney Sean Hayes.