Dawnmarie Souza is an emergency medical technician who got into a dispute with her supervisor. That evening, she sat down at her computer and typed an angry post onto her Facebook page. She called him a "17" -- the company's term for a psychiatric patient -- and mocked him in other ways, according to the ambulance company that employed her. Other employees added sympathetic comments, further criticizing the boss.

Her actions were a clear violation of the company's social media policy, which reads: "Employees are prohibited from making disparaging, discriminatory, or defamatory comments when discussing the Company or the employee's superiors, co-workers and/or competitors." And so she was fired.

This may all seem straightforward enough, but then the plot took an unexpected twist when the National Labor Relations Board (NLRB) filed a complaint against American Medical Response (AMR) the ambulance company that dismissed Souza. The firing was illegal, the NLRB said, and so was the social media policy that led to it. The National Labor Relations Act protects employees' right to discuss their working conditions, it decreed, and it didn't matter whether they did so around a water cooler or over Facebook.

An administrative law judge will begin hearing the case in January, and it's expected to be several months, at least before there's a final decision. But even if it wins its case, the company will have spent untold amounts of money and time, and endured months of the kind of publicity no company ever wants.

And yet, its policy is hardly unusual. Thousands of companies have policies forbidding employees from badmouthing their employers, co-workers, superiors, or competitors on social media. Some have rules against naming their employer at all. Others bar workers from discussing their salaries. Any of these could lead to trouble with the Feds.

A newer, tougher standard

The filing has left employment lawyers scrambling, in part because NLRB practices appear to have changed. "There was a case based on a similar policy that came up about two years ago and the NLRB general counsel declined to issue a complaint," says Seth Borden, a partner in the Labor and Employment group at McKenna Long & Aldridge LLP. Now, he says, the Board has a new general counsel. "The Board has signaled a willingness to take a broader view of employees' rights."

Companies should be concerned about this new direction, he says. "This is the first prominent instance of social media being viewed through the prism of traditional labor law," he says. "It's the tip of the iceberg."

Given the new reality, many employers are wondering whether it would be best to scrap social media policies altogether. But legal experts still agree you're better off with a policy than without one. "I'm encouraging my clients to have and enforce a social network policy in order to prevent disclosure of confidential information, trade secrets, and business plans," says Jerry Lutkus, partner at Barnes & Thornburg LLP. "And these policies should tie in to their anti-harassment and anti-discrimination policies."

Since you do need to have a social media policy, how can you make sure it won't get your company in trouble? Here are some issues to consider:

Avoid 'disparagement'

According to several legal experts, without this one word AMR could probably have stayed out of trouble. "If you took the disparagement language out of this policy, it becomes very hard to argue that it's invalid on its face," Lutkus says. At the same time, he acknowledges, without that wording it would have been hard for AMR to discipline Souza based on her Facebook post.

Have your policy acknowledge the law

One of the simplest ways to make sure your policy won't violate a law is to say so, right in the policy. "Your policy may need protective language that says the application of this policy will be consistent with the National Labor Relations Act," advises Maria L. Petrillo, a member at Eckert Seamans Cherin & Mellott, LLC in Philadelphia. And Borden recommends taking it one step further, and having a blanket disclaimer attached to your entire employment policy that no application of your policy will violate any applicable local, state, or federal law.

Don't cover all the bases

Companies sometimes try to play it safe when writing policies, trying to come up with blanket language that can cover any possible contingency. But that very strategy can get you in trouble if the NLRB sees your policy as overly broad. On the other hand, a policy that's too narrow can leave you unprotected if an employee does something you hadn't thought of. "It's tricky for employers to get that balance between too broad and too narrow," Borden says. "But I think they ought to try."

Understand what's protected

Section 7 of the National Labor Relations Act protects employees' right to engage in "concerted activities" for bargaining, mutual aid, and protection. That means it's especially risky to interfere any time employees discuss working conditions among themselves. Keep in mind, though, that employees who make defamatory or discriminatory statements can lose that protection.

Don't invite trouble

The AMR case began when Souza was ordered to write a response to a customer's complaint about her. She asked to have her union representative present but her boss refused to allow it. "Saying no to a union representative raises a red flag," Petrillo says. Without that, experts agree, the NLRB might not have picked AMR to make an example of.

Plan to review your policy at least every two years

"Case law is changing very rapidly and social media is changing rapidly as well, so it's a moving target," notes Christine Hueber, head of ChristineHueber.com which provides social media services and advice to companies here and abroad. "What was right six months ago may not be right three months from now. Social media policies pose interesting questions, because it is such an intersection of business and private life. And we're still finding our way."