A 1970s-era Texas law that allows parents to show "harmful material" to their children has come under fire after a prosecutor said he couldn't file charges against a man accused of forcing his 8- and 9-year-old daughters to watch hardcore online pornography.

Randall County District Attorney James Farren has asked the Texas attorney general's office to review his decision not to pursue charges in the case, which has prompted at least one lawmaker to vow to change the state's public indecency law.

"Our hands are tied. It's not our fault. I have to follow the law," Farren said Thursday. "The mother of the victims in this case was less than happy with this decision, which I understand. We were less than happy with the statute."

The law apparently was meant to protect the privacy of parents who wanted to teach children about sex education, but it states clearly that parents can't be prosecuted for showing "harmful material" to their children.

Farren said police reported the incident to his office after one of the girls told a counselor in June that her father made them watch adults having group sex and various other acts at his home in Amarillo. The parents of the girls, and their 7-year-old sister, are divorced and share custody.

The girls' mother, Crystal Buckner, wants her ex-husband to be jailed. She said she was stunned to hear from prosecutors and police that nothing can be done.

"I said, 'Are you kidding me?' There's no way. This can't be right," said Buckner, a 30-year-old stay-at-home mother.

The Associated Press typically does not publish the names of parents if it could identify children who might have been abused, but Buckner is seeking publicity about the case. She has printed out copies of the penal code, which she hands out to everyone she meets.

"I want people to know about this. I want parents to be mad and say, 'No!"' she said. "I understand in the '70s everybody wanted the government to stay out of their homes. I don't want to stop parents from having that right to teach sex education, but there's a big difference and there's a line you should not cross when teaching."

The Texas attorney general's office said Thursday that it would be months before an opinion is issued and declined further comment.