A federal judge in Los Angeles ruled yesterday that the National Endowment for the Arts violated the Constitution by requiring grant recipients to sign a pledge that their federally funded work would not be "obscene."

The NEA had argued that it was not restricting free expression because artists could simply give up their grants and seek other sources of funding. But the court found that the certification requirement "is the type of obstacle in the path of the exercise of fundamental speech rights that the Constitution will not tolerate."

While many of the conditions that produced the litigation no longer exist, U.S. District Judge John G. Davies suggested that the court would look askance at future congressional efforts to restrict the type of work that may be funded by the endowment.

"In simple terms, the government may well be able to put restrictions on who it subsidizes and how it subsidizes, but once the government moves to subsidize, it cannot do so in a manner that carries with it a level of vagueness that violates the {Constitution}," the court ruled.

NEA officials had no comment on the decision and would not say whether the agency will appeal.

The impact of the ruling is limited because the endowment stopped requiring grant recipients to sign such pledges in October, when Congress revamped the laws affecting the type of art that may be funded. The new law leaves obscenity determinations to the courts and imposes penalties on grant recipients who are convicted on obscenity charges. The new legislation does not require the endowment to determine whether works may violate obscenity standards. Instead, the endowment may not fund works that violate standards of "decency." NEA Chairman John Frohnmayer has promised that he will not reject any grant on decency grounds.

Yesterday's ruling came in cases filed separately last year by choreographer Bella Lewitzky and the Newport Harbor Art Museum. Lewitzky was awarded a $72,000 grant and the art museum was to receive $100,000. A similar case by the New School for Social Research is still pending in federal court in New York. The certification requirement prompted several other grant recipients, including New York producer Joseph Papp, to reject NEA funding.

Davies ruled that the endowment may be so influential that "if an artist chooses not to be bound by the NEA's obscenity restriction, he will not be able to obtain private funding."

Choreographer Lewitzky told reporters in Los Angeles yesterday her decision to turn down the grant had endangered the future of her company but protected the art world as a whole.

"Most arts organizations our size live on the brink all the time," she said. "You live from paycheck to paycheck, and this has taken away the artists' salaries. It's very hard to pay your rent, your gas, your food bill on a moral issue."

Yesterday's decision suggests that Congress took an unconstitutional approach in the 1990 appropriation by requiring the endowment to determine whether a work may be considered obscene. Davies rejected the endowment's argument that it would stay within constitutional bounds by applying the Supreme Court's obscenity standards. "Simply stated, the NEA is a national-level agency that ... is incapable of applying varying community standards for obscenity," the court said.

Davies held that the certification requirement would have a chilling effect on freedom of expression. That effect is magnified, the court noted, because "the NEA occupies a dominant and influential role in the financial affairs of the art world."

The decision was hailed by People for the American Way, which represented Lewitzky in the litigation. "I think it reinforces the notion that Frohnmayer should not be a decency czar," said Elliot Mincberg, legal director for the group.

Attorney Floyd Abrams, who is representing the New School in its challenge to the certification requirement, said he believes the ruling would be "helpful" if Congress attempts to impose further content restrictions.