The captain, whose identity was withheld, was convicted for violating the Military Criminal Act, according to the Center for Military Human Rights Korea. Under the law, a soldier who commits "sodomy" or "other disgraceful conduct" can face up to two years in prison.
"It is a bizarre clause that only has a perpetrator, without a victim," the group said in a press release, adding the captain had sexual intercourse at a private place under consent.
The defendant, however, will not appeal the ruling, according to an official at the group.
"The captain was fulfilling his military duty and was originally scheduled to be discharged in April," the official said. "If he appeals the ruling he will have to stay in the military without knowing when the legal battle will be finished."
The captain collapsed after the ruling was delivered and was transferred to a nearby hospital but is known to have left the hospital in stable condition, according to the official.
In April, the civic group claimed that Army Chief of Staff Gen Jang Jun-gyu ordered the military to hunt down homosexual soldiers. It said the military carried out a probe to find homosexuals and put some 40 to 50 soldiers on the list.
The Army, however, has denied the allegations, adding that the investigation met all due legal procedures.
Following the ruling, civic groups immediately expressed concerns and criticized the court's decision.
"This unjust conviction should be immediately overturned," said Roseann Rife, East Asia research director at Amnesty International in a press release. "No one should be persecuted based on their sexual orientation, activity or gender identity alone. What counts is their service not their sexuality." (Yonhap)