In the old days, it was routine in rape trials to exonerate the defendant by convicting the victim. Was she, perhaps, wearing too much makeup? How about her walk -- modest as becoming a lady or sashaying like a tramp? If the answers to those questions painted a picture of someone other than Mother Teresa, you had your perfect rape defense: The woman was looking for it.

It is along those now discredited lines that two judges of the District of Columbia Court of Appeals found The Washington Post guilty of being -- brace yourself -- a newspaper. The Post, the court found, "is a newspaper which seeks, among other things, hard-hitting investigative stories." The penalty for this is an approximately $2 million libel judgment and -- until further appeal -- the censorious hand of future suits.

The instant case, as the lawyers like to say, involves a 1979 Post story that Mobil Oil's then president, William Tavoulareas, had "set up" his son in business -- to wit, a shipping company that did business with Mobil. Tavoulareas sued for libel, won in District Court but lost when the judge threw out the verdict. He appealed.

By a margin of 2 to 1, the appeals court reinstated the jury verdict. The Post, the court said, had indeed libeled Tavoulareas. Since the president of Mobil is legally considered a "public figure," something called "actual malice" had to be proved. Judge George E. MacKinnon, searching real hard, found it in, among other things, The Post's penchant for "sensational expos,es." That sort of thing gets rewarded at The Post.

To be perfectly fair, the judge cited more than The Post's alleged weakness for investigative stories. And he did, in a footnote, say that the last thing he wanted to do was discourage investigative reporting. There then followed a sentence of required boilerplate on the importance of the press in our society -- a goose cooked by the decision itself.

Still, like the woman who's held responsible (guilty?) for being a woman, The Post was found guilty for being what it ought to be -- a newspaper. To a whole lot of people, anything worthy of that title practices investigative reporting. If you get what amounts to a franchise -- the First Amendment and, often, a monopoly market -- then you also have an obligation to make a pest of yourself. That means poking around nursing homes and jails, insane asylums and schools, state houses and fire houses and, yes, corporations of enormous power and wealth.

Now maybe you disagree. Maybe you think no newspaper ought to go poking around Mobil, or to respond to a tip about it. But that is a judgment call, as valid, say, as Richard Nixon's conviction that the press should have taken him at his word on Watergate and left well enough alone. The revelations of Watergate, after all, were the fruits of the journalistic ethic the court now deplores; ditto stories about ripoffs in government contracts and rape in the jails. These stories do not come from sitting back and waiting for press releases in the afternoon mail. They come from "hard-hitting investigative" stories of the very type the court now holds against The Post.

If the court thinks that it can have the sort of investigative stories it likes and not the ones it doesn't, then it knows nothing about either journalism or human nature. By imposing a punishment, it -- and the public -- will get none whatever. Already, The Post has spent over $1 million on legal fees and now may face paying about $2 million more in judgments. Is there a story worth that much? Certainly not the one about Tavoulareas. But if the press flinches from that one, why not others? Nursing homes can sue too. Even ones that let old people rot.

The inescapable conclusion is that the panel's conservative majority -- one Nixon appointee and one Reagan appointee -- knows full well the import of its decision. Its lofty Jeffersonian paeans to a vigorous press nothwithstanding, the panel sat, as dissenting Judge Skelly Wright noted, "as some kind of journalism review seminar" and dealt investigative reporting a serious blow. Like a rape victim, the press is condemned for being what it is. But you can only take analogies so far. In this case, it's not the press that was raped. The real victim is the public's right to know.