South Korea's Constitutional Court declined Friday to rule on the validity of a 2015 diplomatic agreement with Japan that aimed to provide funds to the Korean "comfort women" but was deeply unpopular with the Korean public and may have fallen short of being an official treaty.

The court said the bilateral agreement is a "political deal" and its legal power is unclear. Thus, the legal rights of the plaintiffs have not been infringed, the court said, adding that it does not need to judge whether, by concluding the deal with Japan, the South Korean government had violated the Constitution.

The court acknowledged, however, that the "pain" the former comfort women suffered as a result of the deal was "not at all light," given that the government failed to sufficiently solicit their opinions while negotiating it with the Japanese government.