TV anchor Christine Craft won the biggest paycheck of her life last week. A jury nicked her former company, Metromedia Inc., for $500,000 for firing her unfairly.

Craft is not alone in hauling her ex-employer before the bar. Job security is becoming too important to leave entirely in the hands of corporations.

"We have become a nation of employes," a court in Pennsylvania mused five years ago. "For our generation, the substance of life is in another man's hands," raising the question "whether the time has come to impose judicial restriction on an employer's power of discharge."

Union members and government workers have long been protected against arbitrary firings--sometimes too well protected. Lengthy grievance procedures can make it tough to get rid of even an incompetent employe.

Yet it's just as bad to grant employes no protection at all from companies that hire and fire carelessly. Workers risk their financial security when they change jobs; they are trusting their new employer to play fair.

In return for that trust, courts in several states have been ruling that jobs can't be snatched away without warning or cause, or for reasons seen as patently unjust.

Most employers still think in terms of the classic, one-sided contract between worker and boss, laid down by a court back in 1884 Companies, it said, "may dismiss their employes at will . . . for good cause, for no cause or even for cause morally wrong, without thereby being guilty of legal wrong." Applying that doctrine, courts in recent years have allowed the following firings to stand: A power-company guard, suspended for telling a city official that management wasted a lot of money; an engineer fired by Du Pont for writing a novel about a Du Pont-like "Logan Chemical Co.," which bad-mouthed its fictional scientific personnel; a chemist, fired from a cosmetics company after charging in letters to the editor that cosmetics are overpriced.

But David Ewing, author of "Do It My Way or You're Fired!", points to several other, more encouraging cases that defended the rights of fired employes. Among the workers who won their lawsuits: A California woman, fired for refusing to commit perjury to help her employer; a married woman in New Hampshire, fired for refusing to date her foreman; a Connecticut worker, fired for writing an article accusing his company of sabotaging a union grievance procedure; an Indiana man, fired for filing a worker's compensation claim, and an IBM sales manager, dismissed for continuing to date a former IBM sales manager who had gone to work for a competitor.

Federal laws defend workers dismissed for reasons of age, race or sex discrimination, if you can prove your case. The National Labor Relations Act protects people who protest work rules or favor unions.

Nor are companies supposed to fire workers who blow the whistle on violations of about 20 federal laws, including those on coal-mining safety, water-pollution control, clean air and occupational safety and health. But protection lapses if your case isn't filed with the right government agency, sometimes within 30 days of any punitive action the company takes. Several states have recently passed their own whistle-blower protection laws, which Ewing thinks may be more effective than the federal laws.

The Craft case was won partly on an argument that's new to employe lawsuits: fraudulent misrepresentation. The jury felt that the bosses hadn't leveled with Craft. They claimed to want her journalistic skills, but fired her for not being sufficiently young, pretty and stereotypically feminine.

Fraud is more commonly claimed in contract or property cases; applied here, it supports the evolving perception of jobs as a form of property right.

There are some other grounds for lawsuits in some states: if the company fired you after making promises it didn't keep; if your job wasn't properly described when you were hired, or if the company failed to follow its own, written termination procedures when firing you.

But employe rights vary greatly from state to state. "A fired employe has almost no chance of winning in Texas or the Southeast," Ewing says, "but all sorts of chances in Michigan and California." By threatening to sue, some employes manage to sweeten their severance pay, even if the case never comes to court. If you're fired, it may pay to have a chat with a lawyer before cleaning out your desk and quietly picking up your final check.