HONG KONG (MarketWatch) — In the first case of its kind in China, search-engine leader Baidu is facing a lawsuit after a clinic claiming it could make gay men become heterosexual appeared atop its search results.

The 30-year-old plaintiff, referred to in reports by the alias “Xiao Zhen,” is suing both the Chongqing-based Xinyupiaoxiang Clinic and Baidu. Xiao Zhen said the clinic — which was the first result on Baidu BIDU, -0.00% when he searched for “gay treatment” — had a phoney psychiatry license and administered electroshock treatment as part of the purported “conversion therapy,” the Beijing Times newspaper reported Monday.

Xiao Zhen is demanding compensation of more than 10,000 yuan ($1,620) from Baidu and Xinyupiaoxiang Clinic, which he said had infringed upon his health and personal rights.

Baidu responded that the clinic had a business license for “psychological counseling” and that the difference between “counseling” and “treatment” was hard to distinguish, according to an earlier report by state-run Xinhua News Agency quoting the company’s lawyer in the case.

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While the case went to trial on July 31, it garnered little media attention until just recently. A verdict is still awaited, the Beijing Times report said.

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Baidu, unlike its foreign counterparts such as Google Inc. GOOG, -2.37% , doesn’t distinguish between paid search results and organic search results.

In 2008, state broadcaster CCTV ran a two-day series accusing Baidu of massive interference in its search results, including displaying paying brands at top of the results without taking any measure to mark them as advertising.

It also said Baidu engages in “blackmail marketing,” using its dominant market position in China to alter search results so that users can’t find companies which refuse to pay.

At that time, Baidu Chief Executive Officer Robin Li denied any deliberate use of blackmail marketing, but apologized for actions of some managers that may have resulted in some result getting buried.

In 2011, CCTV, again, ran a series of reports alleging Baidu had promoted fraudulent enterprises in its paid search results.

Following the publishing of this report, a Baidu spokeswoman told MarketWatch that the search engine does mark paid search results, either using a “color undertone” or the Chinese word “tuiguang,” which is roughly equivalent to the term “promoted” in English, placing them in the right-hand column or at the top of the page.

However, the CCTV report and other criticism of Baidu’s display of paid results have said it’s difficult to distinguish what constitutes advertising on the site.

As of the second quarter of this year, Baidu held a more-than-70% share of China’s search-engine market, according to research by Beijing-based Enfodesk Analysys International.

The Chinese company hasn’t faced much serious competition since Google closed its mainland Chinese site in 2010 amid a censorship dispute, instead redirecting its mainland users to its Hong Kong site. As a result, Google’s market share has declined to about 12%, compared with over 30% share before its exit.