SEOUL—South Koreans who refuse mandatory military service must be given an alternative, a court ruled, paving the way for a shakeup in a decades-old draft system that many regard as sacrosanct but which has led to the imprisonment of thousands of conscientious objectors.
The decision marks a shift for a nation that imprisons more young men for refusing military service than the rest of the world combined, with some 218 currently behind bars, according to Amnesty International. All able-bodied South Korean men are required...