The law banning the sending of anti-Pyongyang leaflets into North Korea is an unconstitutional infringement on freedom of expression, the unification minister has contended.

Civic groups on Thursday revealed an opinion to the Constitutional Court by Minister Kwon Young-se arguing that the sending of such leaflets is a “political activity,” and that the ban could constitute a violation of the freedom of political activity or expression of political opinion.

The ban has been contested by 27 civic groups. They have requested that the court review the constitutionality of the law prohibiting leaflets from being sent to the North or face a maximum prison term of three years or a fine of 30 million won.

The legislation has been criticized for restricting freedom of expression, but the government at that time countered it as necessary for the safety of people living in border regions because such leafletting could provoke North Korea.

Civic groups in South Korea including those led by North Korean defectors often send large plastic balloons carrying leaflets over the border in what they say is a bid to free the North Korean people from the tyrannical regime with outside information.