Just this week the government filed a lawsuit in a first-of-its-kind case.
The National Labor Relations Board says a woman was fired illegally from her medical technician job after she posted bad comments about her boss on Facebook.
It's not the first time what has been posted online has created problems on the job.
"You have to think to yourself, 'What kind of picture do I want on Facebook that could really come back against me,'" labor attorney Vance Knapp said.
Knapp says it's hard to define where the line is drawn, primarily because technology keeps changing.
"The interesting thing is as soon as a new law comes out it seems like a new social media comes out, so what we are talking about today could be completely different in 2011," Knapp said.
Currently there are laws, both federal and state, that protect employees from being fired because of their social networking sites.
"We have a specific statute that's called the Lawful Off-duty Activities Act, which protects employees who engage in off-duty, off-premise activity. So if they aren't doing it at work - then that act is going to protect them. However, if the employee is using these sites on company time or using company equipment that could be a problem," Knapp said.
Knapp also says employees need to be aware of what their employers social media policies are - that's were employees can get in trouble.
"You certainly have a right to engage in blogging and Facebook, but understand if you don't need a password to access this information it's going to be out there in the internet universe and unfortunately people will Google that information and it could be used against you," he said.
The laws are also different for public employees such as postal workers. Public employers can implement stricter policies on their hiring and firing practices.
His best piece of advice: better to be safe than sorry.
"We have a saying in the law that once it's in writing, it's always there. It's never going to go away and once it's posted on the internet you're never going to be able to get rid of it," Knapp said.
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