Two weeks after South Korea passed a controversial law banning leaflet launches to North Korea, several South Korean civil groups fought back by filing a constitutional appeal on Tuesday.

The recent “anti-leaflet” law, passed on Dec. 14, cracks down on the act of sending informational or propaganda fliers over the border by enacting fines of up to 30 million won (about $27,000) or prison sentences of up to three years.

The law drew international attention and criticism from human rights advocates, who called it a violation of free speech that could have a chilling effect on activism related to North