A landmark antitrust lawsuit went to court in Shanghai Wednesday, the South China Morning Post reported. It stems from a case filed in November 2004 by Sichuan TSUM Power Company against Sony and Shanghai Suoguang Electronics, claiming the Japanese giant uses codes in batteries installed in its products that prevent other companies from making competing batteries. "They take advantage of their top market position and build a technological obstacle," said spokesman Yao Zhen. Sony said the issue is also one of personal safety as poor quality non-Sony batteries can be hazardous. The case could be a warning to multinational companies who may use intellectual property rights or patents to lock out competitors, Yao's spokesman said. China does not have an anti-monopoly law. The Shanghai No1 Intermediate People's Court did not issue a decision Wednesday.