SOME civil libertarians are troubled by the United States Supreme Court's recent ruling that states may ban public nude dancing without trampling on the First Amendment. The court's conclusion is, however, less alarming than the logic Chief Justice William H. Rehnquist used to arrive at it.The state of Indiana's public decency statute prohibits public nudity, even in venues that admit only consenting adults. Almost a decade ago, the owners of the Kitty Kat Lounge in South Bend sued to have the nudity ban overturned, saying that it unconstitutionally restricted expressive conduct. The lounge's owners lost in US District Court in Indiana, but won their constitutional argument when they took the case to the US Seventh Circuit Court of Appeals in Chicago. The prosecuting attorney for St. Joseph County, which includes South Bend, then appealed to the Supreme Court. In his plurality opinion, Chief Justice Rehnquist explained that "nude dancing of the kind sought to be performed here is expressive conduct within the outer perimeters of the First Amendment, though we view it as only marginally so." Nonetheless, he wrote, the state's interest in protecting public morality must override these First Amendment considerations. Justice Antonin Scalia also voted to support the state's authority to ban public nude dancing, but for a significantly different reason. In a concurring opinion, Justice Scalia wrote that "the First Amendment has no application to this case." He is probably more right than wrong here, and certainly more logical than the chief justice. Nude dancing in this context expresses no political message. Its redeeming artistic, social, and cultural values are so minuscule as to defy measurement. Thus, it is arguab ly beyond the scope of constitutional protection. This conclusion, however, applies only to a specific, narrow instance, even if First Amendment absolutists find it dangerously restrictive. Far broader and more worrisome is Rehnquist's view that a state can so readily prohibit legitimate forms of expressive conduct that fall within the "perimeters of the First Amendment," however marginally. When, and for what reasons, may government ban other legitimate forms of expression? THIS question becomes even more acute given the temper of the current Supreme Court. Less than a month before approving Indiana's nudity ban, the court decided the controversial case of Rust v. Sullivan. In this decision, the court upheld the constitutionality of a "gag rule" prohibiting doctors at federally funded family planning clinics from even discussing abortion with their patients. In so ruling, the court completely ignored the late Justice William O. Douglas's reasonable dictum that the "right of the doctor to advise his patients according to his best lights seems so obviously within First Amendment rights as to need no extended discussion." In this case, Rehnquist asserted that when federal money is involved, the government's authority to advance a particular social interest outweighs First Amendment protections. The only major difference between his position here and in the subsequent Indiana case is the issue of governmental funding. But, as Justice Harry A. Blackmun wrote in dissenting from the court's decision in Rust, "until today, the court never had upheld viewpoint-based suppression of speech simply because that suppression was a condition of acceptance of federal funds." The Rehnquist court now seems dangerously inclined to expand government's power to limit legitimate forms of expression at the expense of individual civil liberties. Justice Thurgood Marshall's retirement, announced late last month, will likely accelerate this alarming trend when the court convenes again in October. Unchecked, this increasingly restrictive view of free expression sanctioned by the Supreme Court will significantly undermine the precious rights the First Amendment is supposed to protect for all Americans.