Apparently true: <a href="http://www.usconstitution.net/china.html#Article35" rel="nofollow">http://www.usconstitution.net/china.html#Article35</a>
Also, Article 41:<p><i>Citizens of the People's Republic of China have the right to criticize and make suggestions regarding any state organ or functionary. Citizens have the right to make to relevant state organs complaints or charges against, or exposures of, any state organ or functionary for violation of the law or dereliction of duty, but fabrication or distortion of facts for purposes of libel or false incrimination is prohibited.</i><p><i>The state organ concerned must deal with complaints, charges or exposures made by citizens in a responsible manner after ascertaining the facts. No one may suppress such complaints, charges and exposures or retaliate against the citizens making them.</i><p>It appears that the constitution states that people have these rights, but unfortunately it is the people who constitute the government of the time who protect (or disregard) rights, not a document.  Actions speak louder than words.