IMAGINE YOU and a fellow worker were fired because you "liked" a Facebook post by a former co-worker. The post criticized the employer for allegedly making mistakes on their W-2s resulting in the worker owing additional state income tax.

That's just one of several cases that may come up for discussion at a Philadelphia Society for Human Resource Management seminar here today and tomorrow.

The case, which went before the National Labor Relations Board and was decided on Aug. 22, involved a waitress and a cook at Triple Play Sports Bar and Grille in Waterbury, Conn.

The NLRB found Triple Play violated the National Labor Relations Act (which applies to virtually all businesses) by threatening to fire two employees, then firing them due to Facebook posts.

The NLRB ordered Triple Play to reinstate the employees, give them back pay and rescind or revise its "Internet/Blogging" policy and inform employees. The case is now on appeal in federal court.

But it's not an isolated case. There have been numerous NLRB decisions employers need to be aware of, said Heather Herrington, who specializes in complex commercial and civil litigation as well as labor and employment matters at Jacobs Law Group and helped organize the HR symposium.

The NLRB handed down a decision in December that employers can't restrict use of company email accounts to business-only use after work. The case involved Purple Communications Inc.,which had an email policy prohibiting employees from using the company email system to engage in "activities [with] . . . persons who had no . . . business affiliation with the company."

The NLRB said employees have a presumptive right to use their employer's email systems to communicate about workplace issues, including union organizing. An employer may rebut the presumption only by demonstrating "special circumstances" that make a ban on non-business use of corporate emails necessary to foster productivity or discipline.

The two cases, while unrelated, emphasize the importance of having legally compliant email and social-media policies. Employers should review (and where necessary, revise) their policies to make sure they're not applied in a way that invites NLRB scrutiny, Herrington said.

In recent years, the NLRB has been critical of "overly broad" corporate email and social-media policies that discourage employees from collectively bargaining or exercising free speech. However, the law on social media is unsettled and recent rulings have left employers unsure on how to proceed. Herrington said social media has "become the new water cooler" in the workplace.

Smaller businesses, especially startups, may be especially vulnerable, she said, because they don't typically have HR departments that stay abreast of NLRB decisions and related court cases.

"You as a small business owner have to make sure you're aware of the things that apply to you and what constitute good business practices," Herrington said.

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Note to readers: The Talking Small Biz column will now appear every Monday in the Daily News. You can also follow me on Twitter at @MHinkelman.