Instead, the courts often apply a six-pronged test, developed in a 1986 case called United States v. Dost, to determine whether an image meets the "lascivious exhibition" standard. That test —which requires a court to examine the child's pose and attire, the suggestiveness and intent of the image and other factors— includes one standard on whether the child is naked. However, no single standard under Dost is absolute, and courts must continuously examine potentially illegal images while considering each part of the test.
The leading precedent on child pornography involving clothed minors is a federal case known as United States v. Knox, which involved a pedophile who obtained erotic videos of girls. In that 1994 case, the Federal Court of Appeals upheld the conviction of the pedophile, Stephen Knox, saying explicitly that clothing alone did not automatically mean that images of children were legal.
"The harm Congress attempted to eradicate by enacting the child pornography laws is present when a photographer unnaturally focuses on a minor child's clothed genital area with the obvious intent to produce an image sexually arousing to pedophiles," the court's ruling says. "The rationale underlying the statute's proscription applies equally to any lascivious exhibition of the genitals or pubic area whether these areas are clad or completely exposed."
While adult pornography has some First Amendment protections, there are no such protections for child pornography. Still, some experts have expressed discomfort, in general, at criminalizing clothed pictures of minors.