By Rachel Elson

Speech isn’t actually free in the workplace–and the wrong words can be costly indeed. Follow these rules to keep your company out of trouble.

By the time late October rolls around, you may find that wherever you go–the elevator, the local gym, a café, the kitchen in your office–you’re surrounded by deep discussions around the finer points of Electoral College math, candidate caught-on-video gotchas, federal budget strategies, and any number of other 2012 presidential campaign minutiae.

That’s great for civic engagement–but if you’re the boss, it might be terrible for you.

Political conversations can be delicate wherever they take place (say, Thanksgiving dinner with the in-laws). But in your office, such discussions can be both toxic to the culture and financially damaging to you as an employer.

“No good comes from it,” says Alec Beck, a labor and employment attorney at Ford Harrison in Minneapolis. “All it does is make people mad.”

Situations in which one worker offends another with a political message tend to create the biggest HR headaches, Beck says. But it’s employers’ political actions–whether they come in the form of workplace prohibitions or campaign-related requirements–that are most likely to generate costly legal battles, he explains.

Rule No. 1: There’s No Free Speech at Work

Part of the problem comes when employees assume that they have a right to free speech at work.

They are wrong. The truth is that, outside the public sector, the First Amendment doesn’t really protect employees’ speech in the workplace, attorneys say. “Federal law is straightforward: If you’re a private-sector employer, there are not a lot of restrictions on what you can and can’t do” to restrict speech, Beck says.

But telling employees just what not to say can be problematic as well.

Rule No. 2: Be Careful What You Ban

So can you just tell your workers not to talk politics at all? It’s not quite that simple.

The trouble is that political conversations (especially in their most personal and most inflammatory incarnations) can easily veer into issues of race, gender, age, or religion–the so-called protected classes, spelled out in the federal Civil Rights Act’s Title VII. And you don’t want your well-intentioned policy to appear to be trampling on the rights of members of any of those classes.

For instance, a Memphis lawsuit emerged recently when a worker thought her boss’s anti-Obama remarks were racially motivated.

Rule No. 3: Know Your Local Law

Moreover, political speech and behavior are covered by an uneven, overlapping patchwork of rules.

In addition to the groups protected by Title VII, you may need to worry about labor rules. Is a “Teamsters for Obama” T-shirt a political statement, for instance, or a pro-union statement? The answer probably depends on who’s reading it. But if you try to ban it, you could find yourself going toe-to-toe with the pro-union National Labor Relations Board.

Some state laws also create additional protected groups, or additional restrictions on politics-related behavior. In some states, notes Beck, employers can’t call mandatory meetings or rallies to support a candidate. He says: “In many states, I [as an employer] can’t discriminate against employees who support a candidate I don’t like.”

California, meanwhile, prohibits employers from limiting an employee’s off-duty political activity–even a run for office, says Chas Rampenthal, an Inc. contributor and general counsel at LegalZoom. Bottom line: If you’re thinking of mixing politics and the workplace, you need to have a lawyer on speed dial.

Rule No. 4: Be Consistent

Legal experts suggest that companies offer clear policies–and then enforce them evenhandedly.

An electronic-communications policy could bar employees from using company equipment for personal use. That might be enough to restrict them from following a candidate’s Facebook page, for instance.

Rampenthal also suggests that employers have a broadly enforced nonsolicitation policy, barring workers from collecting money for any cause–whether a political campaign or a charity walkathon.

Beck suggests something different. “What I recommend is that employers have a policy that’s very clear: Any political discussions in the workplace cannot interfere with an employee’s job duties, co-workers’ job duties, or the employer’s business,” he says.

“Then actually enforce it, which is often the hard part.”

Rachel Elson is managing editor at Inc.com. Her work has appeared in Newsweek.com, Dance and Pointe magazines, The Washington Post, Salon.com, People.com, The New York Post and other publications. @rachel_elson