The U.S. Supreme Court on Monday upheld a 2003 federal law, making it a crime to promote or present material considered as child pornography.

The court voted 7 to 2 that a federal appeals court was wrong to find the law ambiguous. The court rejected the argument that one part of the law illegally infringed on free-speech, and that documentarians, movie reviewers or grandparents could be the victims of the law’s standards.

Opponents of the law said that the 2003 legislation was broadly written, so that it could be applied to much appreciated movies such as “Lolita,” “Traffic,” or “American Beauty,” which include adolescent sex. But the government said those films did not constitute child pornography and the new law would not be applied on them.

The provision prohibits the promoting, advertising, distributing and soliciting of material in a way intended to make others believe it contained sexually explicit photographs involving children.

The case involves Michael Williams, who was convicted in a Florida federal court, and arrested in 2004, after exchanging messages in an Internet chat room with an undercover federal agent pretending to be a woman. Williams offered to trade photos of children with the agent, and then posted several sexually explicit images of children. When searching his home, agents found more child pornography photos on his computer.

The newly accepted provision makes it a crime not only to produce and possess child porn, but also making others believe a material contains child pornography, even if the material is innocent.

"Child pornography harms and debases the most defenseless of our citizens," said Justice Antonin Scalia, writing for the majority. “This court held unconstitutional Congress' previous attempt to meet this new threat, and Congress responded with a carefully crafted attempt to eliminate the First Amendment problems we [earlier] identified."