A clause in the immigration law permitting the state to indefinitely detain foreigners facing deportation has been ruled illegal.

The Constitutional Court on Friday declared the constitutional nonconformity of the clause in a six-to-three ruling on the case submitted by the Suwon District Court and the Seoul Administrative Court.

The court said the clause violates the principle preventing excessiveness and infringes upon the physical freedom of detainees.

It said allowing indefinite detention only serves to maintain convenience and conformity in state administration, adding there are many other ways to guarantee that a deportation order is executed, such as a residential restriction, guarantor designation, and deposit requirement.

While judging the clause to be illegal, however, the ruling did not immediately terminate it and instead ordered a revision to be made by May 31, 2025.

Justices Lee Eun-ae, Lee Jong-seok and Lee Young-jin, who opposed the constitutional nonconformity decision, noted that the period of protection remains within its objective in most cases, as well as the existence of an appeals system.