As Facebook and Twitter become as central to workplace conversation as the company cafeteria, federal regulators are ordering employers to scale back policies that limit what workers can say online.
Employers often seek to discourage comments that paint them in a negative light. Don't discuss company matters publicly, a typical social media policy will say, and don't disparage managers, co-workers or the company itself. Violations can be a firing offense.
But in a series of recent rulings and advisories, labor regulators have declared many such blanket restrictions illegal.
The National Labor Relations Board says workers have a right to discuss work conditions freely and without fear of retribution, whether the discussion takes place at the office or on Facebook.
In addition to ordering the reinstatement of various workers fired for their posts on social networks, the NLRB has pushed companies nationwide, including General Motors, Target and Costco, to rewrite their social media rules.
"Many view social media as the new water cooler," said Mark Pearce, the board's chairman, noting federal law long has protected the right of employees to discuss work-related matters.
"All we're doing is applying traditional rules to a new technology."
The decisions come amid a broader debate over what constitutes appropriate discussion on Facebook and other social networks. Schools and universities are wrestling with online bullying and student disclosures about drug use.
Governments worry about what police officers and teachers say and do online on their own time. Even corporate chieftains are finding their online comments can run afoul of securities regulators.
The NLRB's rulings, which apply to virtually all of the private sector, generally tell companies it is illegal to adopt broad social media policies, such as bans on "disrespectful" comments or posts that criticize the employer, if those policies discourage workers from exercising their right to communicate with one another with the aim of improving wages, benefits or working conditions.
But the NLRB has found it is OK for employers to act against a lone worker ranting on the Internet.
Several cases illustrate the differing standards.
At Hispanics United of Buffalo, a nonprofit social services provider in upstate New York, a caseworker threatened to complain to the boss that others were not working hard enough. Another worker, Mariana Cole-Rivera, posted a Facebook message asking, "My fellow co-workers, how do you feel?"
Several of her colleagues posted angry, sometimes expletive-laden, responses.
"Try doing my job. I have five programs," wrote one.
"What the hell, we don't have a life as is," wrote another.
Hispanics United fired Cole-Rivera and four other caseworkers who responded to her, saying they violated the company's harassment policies by going after the caseworker who complained.
In a 3-1 decision last month, the NLRB concluded the caseworkers had been unlawfully fired.
It found the posts in 2010 were the type of "concerted activity" for "mutual aid" that is expressly protected by the National Labor Relations Act.
"The board's decision felt like vindication," said Cole-Rivera, who since has found another social work job.
The NLRB had far less sympathy for a police reporter at the Arizona Daily Star.
Frustrated by a lack of news, the reporter posted several Twitter comments. One said, "What?!?!?! No overnight homicide. . . . You're slacking, Tucson."