* Baidu, China said to jointly stifle pro-democracy speech
* Baidu alleged as "enforcer" of Communist Party policies
* Censorship said to violate U.S. First Amendment (Adds Chinese government comment)
By Jonathan Stempel
NEW YORK, May 18 (Reuters) - Eight New York residents sued Baidu Inc and the Chinese government on Wednesday, accusing China's biggest search engine of conspiring with its rulers to censor pro-democracy speech.
The eight pro-democracy activists claim violations of the U.S. Constitution and, according to the plaintiffs' lawyer, the suit is the first of its type. In an unorthodox move it names not only a company but also the Chinese government as defendants.
The lawsuit was filed more than a year after Google Inc declared it would no longer censor search results in China, and rerouted Internet users to its Hong Kong website.
Baidu spokesman Kaiser Kuo declined to comment.
China's Foreign Ministry, when asked about the lawsuit, said that China "guarantees Chinese citizens' freedom of expression according to the law".
"The way the Chinese government manages the Internet in accordance with the law accords with international norms and is a sovereign matter," ministry spokeswoman Jiang Yu told a regular news briefing on Thursday in Beijing.
"According to international law, foreign courts have no jurisdiction."
According to the complaint filed in the U.S. District Court in Manhattan, Baidu acts as an "enforcer" of policies by the ruling Communist Party in censoring such pro-democracy content as references to the 1989 Tiananmen Square military crackdown.
This censorship suppresses the writings and videos of the plaintiffs to the extent that the materials do not appear in search results, the complaint said.
It also violates U.S. laws because the censorship affects searches here, according to the complaint.
"We allege a private company is acting as the arm and agent of a foreign state to suppress political speech, and permeate U.S. borders to violate the First Amendment," Stephen Preziosi, the lawyer for the plaintiffs, said in an interview.
Preziosi said the alleged censorship also violates federal and New York civil rights laws, as well as New York's human rights law, on the grounds that "an Internet search engine is a public accommodation, just like a hotel or restaurant".
The lawsuit seeks $16 million in damages, or $2 million per plaintiff, but does not seek changes to Baidu's policies.
"It would be futile to expect Baidu to change," Preziosi said. The plaintiffs live in the borough of Queens in New York City and on Long Island.
China's Internet censorship practices are viewed as reflecting its belief that keeping a tight grip on information helps the government maintain control. There have been mounting concerns in China that open dissent on the Internet could contribute to destabilizing the country.
Searches for terms deemed sensitive by Chinese censors are routinely blocked, and search engines such as Baidu voluntarily filter searches. [ID:nL3E7EV117]
China also blocks social networking sites Facebook, Flickr, Twitter and Google's YouTube, and President Hu Jintao has called for additional oversight and "mechanisms to guide online public opinion". [ID:nN06117714]
Google effectively pulled out of China last spring by redirecting inquiries on its main Chinese-language search page to a website in Hong Kong, avoiding direct involvement in any censorship by the "Great Firewall of China".
Renren Inc , which went public on May 4 and runs a social networking site promoted as the "Facebook of China", has warned that its business could be shut down if it failed to comply with prohibitions on content. That would include material that could be considered to impair China's national dignity or was "socially destabilizing".
Baidu's American depositary shares closed up 3 cents on Wednesday at $131.84 on the Nasdaq. They are up almost four-fold since the company went public in 2005.
The case is Zhang et al v. Baidu.com Inc et al, U.S. District Court, Southern District of New York, No. 11-03388. (Additional reporting by Clare Baldwin and Alina Selyukh, Melanie Lee in Shanghai, and Ben Blanchard in Beijing; Editing by Nick Macfie)