A Daegu court said Thursday it has cleared a 60-year-old man of drunk driving charges, ruling that his consumption of alcohol after stopping his car made it impossible to determine if he had been intoxicated while driving.

The man was initially suspected of driving 2.4 kilometers in Daegu with a blood alcohol content of 0.128 percent. He was stopped by police in the city’s Jung-gu district on Sept. 16 at 11:38 p.m. and his breath was tested by police 40 minutes later. The driver was charged based on calculations used by police to estimate his BAC before he had drunk the bottle of soju.

Drivers in South Korea whose BAC is 0.03 percent or higher can be punished for drunk driving, and those with a BAC of 0.07 percent or higher can have their license revoked.

However, the case was complicated by the fact that the defendant consumed an entire bottle of soju inside his car between the time he was pulled over and when he stepped out of the car 39 seconds later. Witnesses reported that he parked erratically and appeared to be staggering as soon as he exited his car.

"Even if the defendant did drink the entire bottle of soju as he claimed, it is unclear why he would appear intoxicated immediately afterward," the court pointed out in its verdict. "But we cannot definitively confirm that he was drunk while driving based on such circumstantial evidence or speculation."

To estimate the man's BAC at the time he was driving, officials used the Widmark formula, which accounts for the passage of time, sex, weight and known consumption to determine prior alcohol levels. But the court ruled there was insufficient concrete evidence to conclusively say that he was intoxicated behind the wheel.

Some drivers have attempted to undermine the results of alcohol testing by immediately drinking large amounts of alcohol when they are pulled over.

South Korean police officers use various means to determine a person's drunk driving when an immediate BAC test is not feasible. These include the Widmark formula, or even having the suspect drink the same amount of alcohol afterward to compare their level of intoxication.