(FORTUNE Magazine) – Or perhaps just taking in a movie with someone else's wife? Laural Allen, 23, and Sam Johnson, 20, had been working for Wal-Mart in Gloversville, New York, for several months when they began dating last January. Neither was a supervisor, and they were employed in different departments. Says Johnson: ''One day in February the store manager called Laural in and fired her. Later she fired me. The reason she gave is that although Laural is legally separated from her husband, she's not divorced. They didn't tell us there's a rule like that.'' The couple has sued for $4 million, plus back pay and reinstatement on grounds of wrongful discharge. Wal-Mart declines to comment while the case is being litigated. Assuming Johnson's story is true, Wal-Mart's action seems such an outrageous breach of privacy that it must be illegal. But maybe not. Employers can fire employees or reject job candidates for any reason that a contract or law doesn't specifically forbid. Federal and state laws prohibit discrimination based on race, religion, age, and sex, but Washington does not protect jobs for those who tango, motorcycle, tease pit bulls, play bridge, or otherwise amuse themselves during off hours. And only a handful of states do. The Wal-Mart case, where morality seems the issue, is unusual. More commonly, employers try to control workers' physical well-being. Why? Cautious, healthy workers cost less. A late 1980s study of 46,000 Du Pont employees showed that each year the average smoker cost the company an additional $960 in medical claims and sick days; the overweight person, $401; the alcohol abuser, $369; a worker with elevated cholesterol, $370; one with high blood pressure, $343. Turner Broadcasting has refused to hire smokers since 1986. North Miami requires applicants to sign an affidavit that they have not used tobacco products for the previous year. Arlene Kurtz, a clerk typist denied a city job because she smokes, has sued. But Florida has no statute protecting smokers. Twenty-eight other states, including Illinois, New Jersey, and New York, have passed laws shielding smokers from such discrimination, urged on by the strange bedfellowship of the tobacco industry and the American Civil Liberties Union. Eight of those states protect a range of activities. New York, for example, makes it illegal to fire an employee who during off-hours engages in sports, games, hobbies, exercise, reading, or watching TV or movies. Lewis Maltby, an ACLU attorney, argues that all legal activities that are not directly related to work should be protected. Says he: ''We all do something dangerous whether it's scuba diving or eating red meat.'' He has a point. Firing an employee for having a couple of drinks after his shift is heavy-handed. An Indianapolis manufacturing company, Best Lock Corp., did just that when it discharged Daniel Winn, a machine operator, several years ago. An alternative might be charging workers for bad habits that ultimately take money from colleagues' pockets. General Mills lowers workers' insurance premiums by as much as 20% if they live healthfully. Among the half- dozen measurements: wearing seat belts; not smoking; drinking moderately or not at all; and controlling weight and blood pressure. Beginning next year, Butterworth Hospital of Grand Rapids, Michigan, will offer its 5,000 employees financial incentives to live healthfully -- and will punish those who don't. Staffers who hew to the proper lifestyle will find up to $25 extra in each biweekly paycheck. Employees who do poorly on tests or who refuse to cooperate will be docked up to $25 every two weeks. Some employees consider the policy overbearing. Says one nurse, Julie Ostrander: ''I resent someone else trying to control my behavior.'' Genes determine weight and cholesterol levels as much as diet does. Should workers be penalized for their parentage? And how does the employer find out whether a worker gets tipsy of a Saturday night? Before adopting such programs, companies ought to consider the consequences thoroughly.