A US judge has dismissed a lawsuit against search engine Baidu and the Chinese government, who have been accused of censoring search results.

According to a report by Reuters, US District Judge Jesse Furman ruled that the dismissal was proper because the defendants had not been properly served with court papers, and China had invoked an international treaty in claiming that service would infringe its sovereignty.

The lawsuit was filed by eight New York-based pro-democracy activists, including writers and video producers, in May 2011, accusing Baidu and China of violating the First Amendment to the US Constitution.

The plaintiffs argued that their content was visible in search engines such as Google, Yahoo, Microsoft’s Bing, and YouTube and sought $16m in damages from Baidu for censoring its content.

According to Reuters, judge Furman said there was "plainly no merit" to the idea that the defendants were properly served.

He said that China had expressly invoked a Hague Convention provision allowing it to refuse service that "would infringe its sovereignty or security."

The judge gave the plaintiffs 30 days to propose another means of serving Baidu, and why the claims against China should not be dismissed.