In a landmark ruling, a Seoul court on Thursday sentenced a 31-year-old pedophile to 15 years in prison and ordered that he be subject to hormonal treatment that suppresses sexual impulses for three years.

It marks the first time that the court has ordered the measure since a bill passed last July that allows hormonal treatment, or “chemical castration,” for convicted child molesters over 19 years of age who are at risk of repeating their crimes against minors under the age of 16.

The defendant, only known by his surname Pyo, was charged with having sex with five teenagers whom he met through a smartphone chat service six times between November 2011 and May 2012. Pyo then threatened to circulate online video footage of them engaged in sexual acts and nude photos of the minors, and also raped them by threatening them with deadly weapons.

After diagnosing Pyo with sexual desire disorder through a medical examination, prosecutors requested in August that the Seoul Southern District Court issue the order.

“(Pyo) committed the crimes against multiple victims for a long period of time. (The court) deems that he has a distorted sexual awareness and excessive sexual desire, which makes it impossible for him to control sexual impulses by himself,” Judge Kim Ki-young said in his ruling.

The court also ordered Pyo‘s information be made available to the public for 10 years and that he wear an electronic monitoring anklet for 20 years after his release from prison.

South Korea was the first country in Asia to adopt this type of treatment, although Germany, Denmark, Sweden, Poland and the U.S.state of California have used it for years. (Yonhap News)