You can be fired for just about any reason, from maintaining a closet Marlboro habit to sporting a "Yes We Can" bumper sticker. (The exceptions: It is illegal to terminate on the basis of race, gender, age, or religion.) That's the startling conclusion of Lewis Maltby's eyebrow-raising Can They Do That? Retaking Our Rights in the Workplace. Here, Maltby dishes on ways employers keep tabs on their workforce, and what you can do to protect yourself.

•Taking a stand makes you a target. "There is no right to free speech when it comes to work," warns Maltby. Translation: You can be fired for simply Tweeting about the cafeteria's ho-hum tuna melts.

Protect yourself: Keep blog, Twitter, and Facebook posts unrelated to work. And exercise some common sense. If your boss, an avid hunter, hangs a moose head in his office, why antagonize him by plastering your cube walls with PETA paraphernalia?

•Your social life is fair game. Your boss can ax you for after-hours activities that rub her the wrong way — dressing up as Sarah Palin on Halloween, for example.

Protect yourself: Before taking any job, get the scoop on a potential boss by talking to current and former employees.

•Your boss spies on you — even when you're at home. If you log on to the office network remotely, any e-mail you send, whether from Gmail or Outlook, passes through your firm's servers and is therefore accessible to your firm.

Protect yourself: Log out of the corporate network before tending to personal business. And do yourself a favor — print copies of all the glowing e-mails you've ever received from the boss. You never know when they'll come in handy.

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