Sections 101(b)(1)(D) and 101(b)(2) of the Immigration and Nationality Act grant preferential immigration status to qualified parents or children of United States citizens and permanent resident aliens. However, because of the definition of “children” and “parents,” preferential status is not granted to an illegitimate child seeking preference through his father, or a father seeking preference through his illegitimate child. Fiallo (plaintiff) and the other plaintiffs in the case were three sets of fathers and illegitimate children seeking preferential immigration treatment for either the father or the child based on their relationship with the other. The plaintiffs challenged the constitutionality of the relevant Sections of the act in federal district court. They were upheld as constitutional, and the Supreme Court granted certiorari on the appeal.