NEW YORK — A special three-judge federal panel refused yesterday to find unconstitutional a law making it a crime to send obscenity over the Internet to children.

Obscenity provisions in the Communications Decency Act of 1996 had been challenged by Barbara Nitke, a photographer who specializes in pictures of sadomasochistic sexual behavior, and by the National Coalition for Sexual Freedom, a Baltimore-based advocacy organization.

They contended in a December 2001 lawsuit brought in U.S. District Court in Manhattan that the law was so broad and vague in its scope that it violated the First Amendment, making it impossible for them to publish to the Internet because they cannot control the forum.

A judge from the 2nd U.S. Circuit Court of Appeals and two district judges heard the facts of the case, Nitke v. Gonzales, and issued a written decision saying the plaintiffs had provided insufficient evidence to prove the law was unconstitutional.

The panel noted that evidence was offered to indicate at least 1.4 million Web sites mention bondage, discipline and sadomasochism, but the judges said that evidence was insufficient for them to decide how many sites might be considered obscene.

The judges said the evidence also was inadequate for them to determine how much the standards for obscenity differ in communities across the United States.

The court said it was necessary to know how much the standards vary to decide if those creating Web sites would be graded for obscenity unfairly when compared with those who market traditional pornography and can control how they distribute the material.

As the law stands, a communication is obscene if according to each community's standards it appeals to the prurient interest, depicts or describes sexual conduct in an offensive way and lacks serious literary, artistic, political or scientific value.

The law requires that those sending the communications take reasonable actions to restrict or prevent access by children to obscenity, sometimes by using a verified credit card, debit account or adult access code as proof of age.

Although the U.S. Supreme Court in Reno v. ACLU (1997) struck down provisions of the CDA that criminalized indecent and patently offensive online communications, the challenge heard by the special court involved obscenity.

Nitke, who has exhibited her work for more than 20 years, said she would appeal the ruling.

"I'm appalled," she said. "I think it's vitally important to keep the Internet free for education, the arts and open discussion on sexual targets."

The National Coalition for Sexual Freedom also was disappointed with the ruling, spokeswoman Susan Wright said.

"Personal Web sites and chat groups that include discussions and images of explicit sexuality are at risk of prosecution," she said. "Basically, we proved we're at risk of prosecution, and speech has been chilled because people are afraid to put anything sexual on their Web sites."

Group lawyer John Wirenius said in a statement that the court declined to find the law unconstitutional "by setting a standard so high that no plaintiff could have met it."

"They required us to prove facts that the government has refrained from making a paper trail on for 30 years," he said.

The National Coalition for Sexual Freedom works to change antiquated laws, oppose censorship of consensual sexual expression and help people who are facing the threat of prosecution or legal action, its Web site says.