A South Korean court on Wednesday delivered a verdict of “not guilty” to a scholar charged with defaming so-called comfort women, who were forced into wartime brothels for the Japanese military, in her controversial book on the subject.

The case at the Seoul Eastern District Court involves Park Yu-ha, a professor of Japanese literature at Sejong University in Seoul, who was sued by a group of former comfort women for having disputed the coerciveness of the comfort women system and depicting some of them as “voluntary prostitutes.”

“Freedom of expression is a basic right guaranteed by the Constitution,” the court’s presiding Judge Lee Sang-yoon said, according to Yonhap News Agency, adding that it “should be protected whether it’s right or wrong.”

Prosecutors appealed the case to a higher court on Thursday.

Last month, South Korean prosecutors sought a three-year prison term for Park, 59, who was indicted in November in 2015 over her book “Comfort Women of the Empire,” published two years earlier.

In a separate case, the same court in January last year ordered Park to compensate nine former comfort women 10 million won ($8,300) each for the mental distress they suffered due to her book.

In February 2015, the court also ordered her to delete some passages from the book, including one that describes some of the victims as “voluntary prostitutes,” in order to continue sales.

Park released a second version of the book after redacting 34 sections and has distributed it free of charge on her website since last year, according to Yonhap.

Many comfort women were from the Korean Peninsula, which was under Japanese colonial rule from 1910 to 1945.