American advocates for pornography often cite the First Amendment to the United States Constitution, which guarantees freedom of speech; however, under the Miller test established by Miller v. California, anything lacking "serious literary, artistic, political, or scientific value" is generally not protected. However, the Supreme Court of the United States held in Ashcroft v. Free Speech Coalition (2002) that pornography which involves consenting adults is protected by the First Amendment, even if the models "appear to be" minors but are, in fact of lawful age, and thus has seen to protect the majority of, but not all pornography on the basis of first-amendment law.
https://en.wikipedia.org/wiki/Pornography_in_the_United_States