Early in college, Ou Jiayong had already learned two things. One, textbooks can be wrong. And two, it can be hard to change them — especially on topics as sensitive in China as homosexuality. In 2016, during her first year at South China Agricultural University in her hometown, Guangzhou, she stumbled across a psychology textbook that described being gay as a mental disorder. As a lesbian, Ms. Ou felt that was unacceptable, but the complaints she made went nowhere.

So Ms. Ou, who also uses the name Xixi, brought a lawsuit demanding that the publisher remove the reference and publicly apologize. Her case has renewed the conversation about tolerance and human rights in a country where discrimination based on sexual orientation is rampant and where homosexuality has long been seen as incompatible with the traditional emphasis on marriage.

In a letter to the judge, Ms. Ou, now 23, recalled being “deeply stung” when she read the textbook. “It brought back memories of being laughed at by my classmates because of my homosexuality,” she wrote in the letter, which her lawyer read aloud in court this summer, three years after the suit was filed.

The judge was unswayed. Last month, the court in Jiangsu Province in eastern China ruled in favor of the publisher, Jinan University Press, saying the content did not “contain factual errors.”

Ms. Ou’s case stunned many people who had no idea that some textbooks still classified homosexuality as a disease, said Peng Yanzi, director of L.G.B.T. Rights Advocacy China, an influential group that has led many awareness-raising campaigns. Citing a survey that a research group conducted in 2016 and 2017, out of the 91 psychology textbooks used in Chinese universities, almost half of them said that homosexuality was a type of disease. Several have been amended, Mr. Peng said, but “many more” remain.

A hashtag about Ms. Ou’s case on Weibo, a popular social media platform, generated 26.7 million views, and several Chinese newspapers covered the hearing in July. Three weeks after the verdict, a school in Jiangsu said it would amend a health education manual after an internet user highlighted a phrase in it that said: “Homosexuality goes against the laws of nature.” Read more via New York Times