South Korea's Constitutional Court has ruled that the country must allow alternative social service for people who conscientiously object to military service, which is currently mandatory for able-bodied males.
The ruling today requires the government to introduce alternative service by the end of 2019.
It was hailed by activists as a breakthrough that advances individual rights and freedom of thought.
It is also likely to trigger a heated debate in a country which maintains a huge military to counter North Korea threats, and where many have accused conscious objectors of attempting to evade the draft.
Hundreds of conscious objectors are imprisoned in South Korea each year, serving terms of 18 months or longer.
Most are Jehovah's Witnesses who refuse to serve in the military on religious grounds.