James v. Boise, 577 U.S. ___ (2016)
Under federal law, a court has discretion to “allow the prevailing party, other than the United States, a reasonable attorney’s fee” in a civil rights lawsuit filed under 42 U.S.C. 1983 or 42 U.S.C. 1988. The Supreme Court has interpreted section 1988 to permit a prevailing defendant to recover fees only if “the plaintiff ’s action was frivolous, unreasonable, or without foundation.” The Idaho Supreme Court concluded that it was not bound by that interpretation and awarded attorney’s fees under section 1988 to a prevailing defendant without first determining that “the plaintiff ’s action was frivolous, unreasonable, or without foundation.” The fee award rested solely on that court's interpretation of federal law; the court explicitly refused to award fees under state law. The Supreme Court reversed. Section 1988 is a federal statute; once the Supreme Court has spoken, it is the duty of other courts to respect that understanding of the governing rule of law. If state courts were permitted to disregard the Court’s rulings on federal law, “the laws, the treaties, and the constitution of the United States would be different in different states, and might, perhaps, never have precisely the same construction, obligation, or efficacy, in any two states."
State supreme courts are bound by the U.S. Supreme Court's interpretation of federal statutes, including those that permit a prevailing defendant to recover attorney's fees.