A more thorough explanation:

A facial challenge is a legal claim that a statute is unconstitutional on its face, meaning that it always operates unconstitutionally. This is different from an as-applied challenge, which argues that a law is unconstitutional as applied to a particular situation or party.

For example, a group may bring a facial challenge to a law that restricts free speech, arguing that the law is always unconstitutional because it violates the First Amendment. On the other hand, an individual may bring an as-applied challenge to the same law, arguing that it is unconstitutional as applied to their specific speech.

Facial challenges can also be used in other legal contexts, such as in challenges to jury selection procedures. For example, a defendant may bring a facial challenge to a law that allows peremptory challenges in jury selection, arguing that the law always operates unconstitutionally because it allows for discrimination based on race, ethnicity, or sex.