The Constitutional Court has found a law enforcing aggravated penalties on repeat DUI offenders unconstitutional.

The court reached the opinion on Thursday in a seven to two vote among its justices regarding a provision of the Road Traffic Act known as the "Yoon Chang-ho Act."

Under the law, people caught driving under the influence or those who refuse to take the breathalyzer test two or more times are subject to two to five years in prison or fines between ten million and 20 million won.

A majority of the judges found the law to be in violation of the principle of proportionality between responsibility and punishment.

They said that without a prescriptive period, offenders may be subject to excess penalties based on a violation committed a very long time ago. The judges also found the minimum sentence of two years and ten million won fine imposed unilaterally to be quite harsh.

The court instead called for alternative measures to address repeated DUIs, such as educational programs and automotive devices that can shut down the engine when the blood alcohol level exceeds a certain limit.

With the latest ruling, the Yoon Chang-ho Act, named after a DUI victim, has essentially been invalidated.