WASHINGTON – The new attorney general, Alberto Gonzales, has launched a wide-ranging review of federal law aimed at strengthening the hand of federal prosecutors who go after adult pornography that is violent or degrading enough to be considered obscene.

But the move, along with Mr. Gonzales’s recent declaration that the aggressive prosecution of obscenity will be a top priority for his Justice Department, is being greeted coolly by groups that campaign against obscenity. His predecessor, John Ashcroft, announced a similar push with great fanfare. The groups that applauded him at the time now say he did not deliver.

“John Ashcroft did not come through as we anticipated,” said the president of the group Morality in Media, Robert Peters. “People concerned about obscenity were not very happy about the results in the first four years of President Bush,” he said.

“We are optimistic, but cautiously so,” said the senior analyst for the press and sexuality at Focus on the Family, Daniel Weiss. “We have to wait to see whether it actually materializes.”

Likewise, the adult entertainment industry says it is “concerned” but “not panicked” by Mr. Gonzales’s announcement, given the track record of the Bush Justice Department.

“The industry continues to grow. I don’t think anyone is panicking. But people are very concerned that it’s a waste of taxpayer money,” said Michelle Freridge, the executive director of the Free Speech Coalition, a trade group representing the adult entertainment industry. Ms. Freridge estimates the industry to be worth $10 billion to $16 billion.

With pornography becoming more mainstream, community attitudes loosening, and new technologies allowing producers to circumvent neighborhood stores, obscenity prosecutions are becoming more challenging than ever.

Mr. Gonzales has ordered a “thorough and comprehensive” review of all prosecutorial powers, and he is particularly concerned about whether the law needs to be changed to keep up with evolving technology, his spokesman, Kevin Madden, said yesterday.

“The attorney general has instructed the legal experts on his staff to review our current laws to see if they can be improved or strengthened in an effort to combat obscenity,” Mr. Madden said.

New technologies in Internet-based video streaming and age-verification features are making it more difficult to show that explicit materials can fall into the hands of children, or be seen by people who do not wish to be exposed to it.

Likewise, the “community standards” used by courts to determine whether material is obscene are becoming more tolerant of sexually explicit images in many places.

“He tried. He really did,” said Ms. Freridge of Mr. Ashcroft’s efforts, which included hiring new investigators and attorneys, as well as holding special training sessions. “And he did have some prosecutions, but because the culture is changing, the laws didn’t apply as well, and he couldn’t get as many prosecutions as he wanted.”

While federal prosecutors focused most of their attention on child exploitation, they were slower to prosecute pornography that is extreme enough to fall outside of constitutionally protected speech and into the legal definition of obscenity.

Such materials generally include violent pornography or images that are considered extremely degrading, such as those involving defecation.

Activists say a failure to prosecute the distribution of obscenity has led to a cultural climate in which pornography is more readily accepted and available on cable television, in video rental stores, and in hotel chains.

When Mr. Bush chose Mr. Ashcroft as his first attorney general, family values advocates were optimistic that the man who made headlines when he covered up an exposed breast of the “Spirit of Justice” statue at the Justice Department would exhibit similar zeal on behalf of their cause. They expected a return to the Reagan era, when obscenity cases were brought regularly, until the Clinton administration turned the focus almost exclusively onto child pornography and exploitation.

The Justice Department says it obtained 38 convictions during Mr. Bush’s first term. It touts the number as an 850% increase over the four convictions obtained in eight years under President Clinton. But activists say only two of those cases were major prosecutions – and one, against a company called Extreme Associates, was dismissed by a judge. Mr. Gonzales said he will appeal.

Activists add that many of the convictions stemmed from only a handful of distribution rings, and many were aimed primarily at child exploitation, rather than at the distribution of adult obscene material. “It didn’t pan out the way it appeared it might when he first started his term in office,” said Mr. Weiss, of Mr. Ashcroft’s tenure.

Activists say they are perplexed about why there were not more prosecutions. Some wonder whether government lawyers were not sufficiently passionate about the issue, or whether the department was simply overwhelmed with a focus on combating terrorism.

“I don’t want to be overly hard on John Ashcroft. I think he meant well. I really do. I think it was his intention to accomplish a lot more on the obscenity front than was accomplished,” said Mr. Peters, whose group maintains an on-line obscenity tip-line, which has registered more than 50,000 tips since 2002.

In a speech last month to the Hoover Institution, Mr. Gonzales said he would aggressively prosecute purveyors of obscene materials. He linked the task to the advancement of human dignity.

Critics of the policy say the federal government should focus exclusively on child pornography – cases in which children have been harmed and exploited.

“Why is he wasting limited government resources on trying to prove legal adult entertainment is obscenity when there is so much work to be done on combating child pornography?” the executive director of the Association of Adult Sites Advocating Child Protection, Joan Irvine, asked in a statement.

Anti-obscenity advocates say adult pornography hurts children by hurting marriages and encourages child exploitation by showing images of adults posing as children.

The adult entertainment industry is also concerned about recent congressional hearings into whether pornography feeds addiction, Ms. Freridge said.