Two internet firms--Tencent and Qihoo met in Beijing’s Supreme Court Tuesday. Qihoo is accusing Tencent of abusing of its dominant position in the market.

It is the first internet anti-monopoly case heard by the Supreme Court since the anti-monopoly law was released six years ago. But it’s not the first time the two firms have gone to court. The three year old battle is over whether Tencent used its leader position to block users from using Qihoo’s software. The government had stepped in to stop the dispute, but the war of words in the media continued. Now the two firms are fighting it out in court. If Qihoo wins, Tencent will need to pay 150 million yuan, or 25 million U.S. dollars to Qihoo, making the most expensive settlement in China’s internet history. The trial wraps up Tuesday.

The Qihoo vs Tencent case has a very high profile because the two companies are so publicly at loggerheads, also because it’s so rare to see an anti-monopoly case in the internet industry. Let’s listen to one legal expert’s opinion.

"The abuse of a dominant position refers to a firm, which has a monopoly role in a certain industry, suppresses its competitors through pricing and other market measures. / To judge if a firm has a dominant position, it is necessary to clarify the range of the market, which we call it the related market. / If a firm abuses of a dominant position is a related market, then it needs to compensate its competitors’ losses, generally it should be economic compensations." Said Qang Yong, associate professor of School of Humanities and Social Science of Tsinghua University.

The main argument is about the definition of market-- Qihoo thinks it should be China’s mainland, where Tencent’s QQ products have 90% of the market. But Tencent says the relevant market should be the global market--where its market share is not dominant. The two sides will argue over this in the trial.