Public airports may not totally ban leaflet distribution or solicitation of contributions, the Supreme Court said yesterday, striking down as unconstitutional a Los Angeles ordinance prohibiting all "First Amendment activities" in the city's main terminal.

The court, in a unanimous decision written by Justice Sandra Day O'Connor, said the sweeping ordinance, creating "a virtual 'First Amendment Free Zone' " at the airport, could not be justified by any conceivable government interest.

But the court declined to decide the question most airport operators have wanted it to answer for nearly two decades: Whether government-run airports have discretion to place restrictions on solicitors and pamphleteers.

In another First Amendment case decided yesterday, the court struck down 8 to 1 a Houston ordinance that made it unlawful for anyone to verbally "interrupt" police officers in the course of their work.

Justice William J. Brennan Jr., writing for the court, said the ordinance "criminalizes a substantial amount of constitutionally protected speech" and it gave police "unconstitutional discretion" in enforcing it.

The Los Angeles airport case, Board of Airport Commissioners v. Jews for Jesus Inc., began in 1984 after a Jews for Jesus minister was stopped by police from distributing free religious literature on a pedestrian walkway in the nation's third busiest airport.

Los Angeles officials said the ordinance was valid because the airport was not a traditional public forum, such as a park or sidewalk, nor one created by government designation for public use, such as public schools or state legislature grounds. Any government ban on speech in such locales bears a heavy burden of proving a compelling government reason to do so.

The airport, according to its owners, was more like a government office building, a nontraditional public forum, where regulation of speech should be upheld if it is reasonable and evenly applied.

O'Connor said the ordinance was unconstitutional on its face and the court did not have to engage in further analysis. The airport resolution, O'Connor said, "prohibits even talking and reading, or the wearing of campaign buttons or symbolic clothing. Under such a sweeping ban, virtually every individual who enters {the airport} may be found to violate the resolution by engaging in some 'First Amendment activity.' "

Justice Byron R. White, joined by Chief Justice William H. Rehnquist, joined the court's opinion but said the question of the ability of airports to place some restrictions on soliciting and leafleting should not have been "postponed for another day." White said he would "suggest" that the opinion "should not be taken as indicating that a majority of the court considers" the airport "to be a traditional public forum."

Arnold D. Kolikoff, an attorney who worked on a brief for the Airport Operators Council International (AOCI), said airport owners would "have to wait for another day" for guidance from the court on how to handle groups who want to solicit there.

"There are decisions {from lower courts} that hold that airports are public forums," Kolikoff said, and "it was the AOCI position that they were wrong, but airports don't have the specific direction from the Supreme Court that those decisions were wrong."

The Houston case, Houston v. Hill, began in 1982 when a police officer saw a man in the middle of the street blocking traffic. The officer summoned the man, who began to act strangely, twitching and making gutteral noises. The man, it turned out, had a medical problem. When he began to walk away, the officer grabbed his shoulder to stop him.

It was at that point that Charles Hill, a civil rights activist who knew the man, spoke up, saying repeatedly: "Leave him alone, he didn't do anything wrong. Why don't you pick on someone your own size."

The officer arrested Hill under the Houston ordinance, which says it is a misdemeanor to "in any manner . . . interrupt any policeman" in the course of his duties. Hill, who had been arrested twice before under the same law, was found not guilty and sued, arguing that the law was unconstitutionally broad.

A trial court ruled against him, but the full 5th U.S. Circuit Court of Appeals reversed, ruling 8 to 7 that the ordinance went too far.

Brennan, writing for the court in yesterday's 8 to 1 decision, agreed. The Houston ordinance, he said, was not "narrowly tailored to prohibit only disorderly conduct or fighting words" and was "not limited to . . . obscene or opprobrious language, but prohibits speech that 'in any manner . . . interrupts an officer.'

"The Constitution does not allow such speech to be made a crime," Brennan said. "The freedom of individuals verbally to oppose or challenge police action without thereby risking arrest is one of the principal characteristics by which we distinguish a free nation from a police state."

Brennan said the ordinance was "violated scores of times daily yet only some individuals -- those chosen by the police in their unguided discretion -- are arrested." Brennan said police could not have "unfettered discretion to arrest individuals for words or conduct that annoy or offend them."

"We are mindful that the preservation of liberty depends in part upon the maintenance of social order. But the First Amendment recognizes, wisely we think, that a certain amount of expressive disorder not only is inevitable in a society committed to individual freedom, but must itself be protected if that freedom would survive."

Justice Lewis F. Powell Jr., joined in part by four justices, concurred in the ruling but said the majority tilted too much against legitimate governmental concerns.

While the ordinance impermissibly punishes speech, Powell said, "I question the implication of the court's opinion that the First Amendment generally protects verbal 'challenges directed at police officers.' " Those challenges, he said, often are "functionally indistinguishable from conduct that the First Amendment does not protect.

"For example, he said, "I have no doubt that a municipality constitutionally may punish an individual who chooses to stand near a police officer and persistently attempt to engage the officer in conversation while the officer is directing traffic at a busy intersection."

The lone dissent in the Houston case was written by Rehnquist.