When an art Institute in Philadelphia displayed Robert Mapplethorpe’s homoerotic photographs, it was subsidized by the National Endowment for the Arts.

When an art museum in Cincinnati displayed the photos, it was raided by police and hit with an obscenity indictment by a local grand jury. Its director could face a year in jail.

This is the reductio ad absurdum of the brouhaha that erupted last year, fanned by the Republican right in Congress, over the arts endowment’s grant of $30,000 to the Institute of Contemporary Art in Philadelphia for a retrospective of Mapplethorpe’s work.

The indictment provides fresh evidence of the foolishness of all obscenity laws (except narrowly drawn laws against child pornography) that criminalize the sale or display of sexually explicit materials to consenting adults.

But silly as it is legally, the Cincinnati case lends weight to the view that some of the Mapplethorpe photographs are so deeply offensive to so many citizens that tax dollars should not be used to subsidize their exhibition.

The finding by a randomly chosen grand jury that seven of the 125 photographs were obscene suggests that, however admired by art connoisseurs, these works are anathema to average folks whose taxes paid for the Philadelphia exhibit.

The suggestion is not conclusive. These grand jurors, like the congressmen caterwauling about dirty art, may be more easily offended than the public at large-which, one hopes, can tolerate a trickle of federal money to finance some art that may be challenging or even shocking.

The dispensers of federal art money should reflect, nonetheless, on how Mapplethorpe’s shots of a forearm shoved into an anus and a man urinating into another’s mouth played in Cincinnati the next time someone comes looking for a federal grant to display similar works.

Neither Censor Nor Fund

The public should not be allowed to censor art that it hates. But it should not be expected to pay for that art either.

This does not mean that Congress should adopt proposals to bar the arts endowment from using federal money to promote, display, or produce "obscene or indecent" materials-let alone the Republican right’s blunderbuss effort to defund all "depictions of sadomasochism, homoeroticism, the exploitation of children, or individuals engaged in sex acts" and materials that denigrate any "religion or non-religion" or "race, creed, sex, handicap, age, or national origin."

To the contrary, the happiest consequence of the whole Mapplethorpe controversy was President George Bush’s statement in March opposing the congressional ban for which the right has been clamoring.

The president said he was "deeply offended by some of the filth that I see into which federal money has gone," but would rather trust the judgment of arts endowment Chairman John Frohnmayer "than risk censorship or getting the federal government into telling every artist what he or she can paint or how she or he might express themselves."

If the president’s rhetoric about censorship was a bit overblown, it was close enough to the mark. It was heartening to see him for once standing up for the First Amendment values that he so blithely trampled in calling for a constitutional amendment to allow prosecution of flag desecraters.

While there is no First Amendment entitlement to a federal subsidy, an inflexible decree disqualifying some people from receiving grants that are available to others, based on the content and viewpoint of their expression, would be constitutionally troublesome.

Hammering a Gnat

It would also be bad policy. A simple ban on funding of obscene art would be redundant. The arts endowment already has such a policy. And a wider ban that also covered "indecent" art would strike at a gnat with a sledgehammer.

Only a handful of the thousands of works subsidized by the arts endowment have been considered indecent by enough people to generate public controversy. An act of Congress aimed at screening out this handful might unnecessarily put museums that rely on federal money in fear of sponsoring any exhibition any part of which might prove offensive to some hypersensitive minority.

The task for the arts endowment is the delicate one of distinguishing works of artistic merit that may challenge or shock from those likely to enrage. This calls not for broad legislative prescription but for good judgment and a sense of balance.

The problem with the proposed congressional curbs on the arts endowment mirrors the problem with criminal laws against obscenity: They attempt to define the undefinable.

While the Supreme Court has essayed several verbal formulas over the years to specify the category of expression that is obscene and therefore unprotected by the First Amendment, none has greatly improved on the definition immortalized by the late Justice Potter Stewart.

Like the Stewart test-"I know it when I see it"-the Court’s current definition, and all other definitions of obscenity, suffer from incurable vagueness. Indecency is an even more nebulous concept.

The variousness of erotic expression and of the contexts in which it is displayed defy evenhanded application of any definition seeking to separate the permissible from the forbidden. And the conflicting passions roused by Mapplethorpe’s photos are a reminder that, in the words of Justice John Marshall Harlan, "one man’s vulgarity is another’s lyric."

This leaves purveyors of pornography, galleries that show sexually graphic art, and bookstores that sell sexually explicit volumes to guess at whether their actions are constitutionally protected or criminal.

It also leads to gross disparities in enforcement of the law, exemplified by the Cincinnati indictment for showing, to adults only, works that had previously been shown by museums and galleries all over the country.

Justice Stevens’ Rule

For these reasons, Justice John Paul Stevens, no First Amendment absolutist, concluded in a 1987 dissent that "government may not constitutionally criminalize mere possession or sale of obscene literature, absent some connection to minors, or obtrusive display to unconsenting adults."

The exceptions are important. Stevens would allow narrowly drawn laws against selling child pornography to dry up the market for materials the very creation of which involve crimes against children.

He would also leave government room to combat moral and aesthetic pollution of the civic environment by restricting the time, place, and manner in which sexually explicit materials-including those not alleged to be obscene-may be marketed and displayed.

Thus Stevens has upheld a zoning law designed to protect neighborhoods by limiting the location of adult movie theaters. And he upheld the Federal Communications Commission’s rule against broadcasting certain "dirty words" on afternoon radio, when children might tune in.

"We simply hold," his plurality opinion in the FCC case said, "that when the Commission finds that the pig-has entered the parlor, the exercise of its regulatory power does not depend on proof that the pig is obscene."

There is no perfect way to accommodate the rights of those who want to produce, market, and see sexually explicit works with the interests of the many who object to having such works subsidized with their taxes or shoved in their faces. But the accommodations proposed by President Bush for federal funding policy and by Justice Stevens for application of the First Amendment aren’t bad.

Sometimes the system works. It will have worked pretty well in the matter of Mapplethorpe if the president sticks to his guns, Congress backs off after making more noise, the arts endowment thinks twice about funding works likely to outrage the public, and the Cincinnati obscenity case is laughed out of court.