28 U.S.C. § 1257 : US Code - Section 1257: State courts; certiorari

      (a) Final judgments or decrees rendered by the highest court of a
    State in which a decision could be had, may be reviewed by the
    Supreme Court by writ of certiorari where the validity of a treaty
    or statute of the United States is drawn in question or where the
    validity of a statute of any State is drawn in question on the
    ground of its being repugnant to the Constitution, treaties, or
    laws of the United States, or where any title, right, privilege, or
    immunity is specially set up or claimed under the Constitution or
    the treaties or statutes of, or any commission held or authority
    exercised under, the United States.
      (b) For the purposes of this section, the term "highest court of
    a State" includes the District of Columbia Court of Appeals.