In the United States, child pornography is prohibited under 18 U.S.C. Chapter 110, Sexual Exploitation and Other Abuse of Children. While this law defines child pornography as “depictions of a minor engaging in sexually explicit conduct,” the actual definition of what is a pornographic image is somewhat more subjective. Many court cases now use “Dost factors” (named after the U.S. v. Dost case in 1986) to determine whether an image is pornographic: these factors ask whether the focal point of the visual depiction is the child’s genital region; whether the setting of the image is sexually suggestive; whether the child is posed unnaturally or in inappropriate attire; whether the child is nude, semi-clothed or fully clothed; whether the picture indicates the child’s willingness to engage in sexual activity; and whether the image is intended to elicit a sexual response in its consumer or viewer. Notwithstanding the popularity of these factors, the U.S. Supreme Court has also stated that fully clothed images may constitute child pornography.

In recent years, much attention has been given to the presence and availability of child pornography on the Internet. Laws such as the Child Online Protection Act (47 U. S. C. §231) and the Children's Internet Protection Act (47 U.S.C. § 254) outlaw child pornography and cover new media such as websites and other online forms of child porn.

Prosecution of child pornographers can be pursued through many agencies, which include the FBI, the Department of Justice, the U.S. Postal Inspection Service, U.S. Customs, the U.S. Attorney General, state attorneys general, state and local law enforcement, and local prosecutors. The government often participates in sting operations to catch child pornographers and consumers of child pornography. Consumption of child pornography can lead to a maximum penalty of five years in federal prison, while distribution of child pornography has a maximum penalty of 15 years in federal prison.