A 1970s law that allows parents to show "harmful material" to their children prevented a Texas prosecutor from charging a man accused of forcing his eight and nine-year-old daughters to watch hardcore porn.
Now 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 politician 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," Mr Farren said.
"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 was apparently meant to protect the privacy of parents who wanted to teach children about sex education, but it states clearly that parents cannot be prosecuted for showing "harmful material" to their children.
Mr Farren said police reported the incident to his office after one of the girls told a counsellor in June that her father made them watch adults having online group sex and various other acts at his home in Amarillo.
The parents of the girls and their seven-year-old sister are divorced and share custody.
The girls' mother, Crystal Buckner, said she wanted her ex-husband to be jailed and was stunned to hear from prosecutors and police that nothing could be done.
"I said, 'Are you kidding me?'. There's no way. This can't be right," said Ms Buckner, 30.
Ms Buckner 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 it would be months before an opinion was issued and declined to comment further.
