A Wal-Mart Stores Inc. (WMT) worker said he was disciplined forusing Facebook to rail against a boss's “tyranny.” A crime reporterin Tucson, Arizona, was fired for using Twitter to taunt that thecity had too few homicides.

The National Labor Relations Board, which acts on unfair-laborpractices, has reviewed 129 such cases since 2009 involving socialmedia and the workplace, most filed this year, according to a studyto be released today by the U.S. Chamber of Commerce, the nation'slargest business lobbying group.

The five-member labor board and its general counsel have sidedwith employers in some cases, agreeing workers can be fired forgratuitous “griping” about the boss. In other circumstances, thegovernment has contended employees were exercising a right to speakout about workplace conditions. The NLRB risks creating a right toTwitter-bomb the boss with online insults, said Michael Eastman,who prepared the study for the Washington-based Chamber.