the tax law, and is not a defense to a charge of "willfulness", even if that belief is genuine and is held in good faith. The Supreme Court reiterated that a finding of willfulness in a federal criminal tax case requires proof (1) that the law imposed a duty on the defendant, (2) that the defendant knew of this duty, and (3) that the defendant voluntarily and intentionally violated that duty. In explaining how the willfulness element must be proven, the Court distinguished arguments about constitutionality of the tax law from statutory arguments about the tax law. In an opinion by Justice Byron White, the Court ruled that the defendant's belief that the tax laws were unconstitutional was not a defense, no matter how honestly that belief might have been held. To the contrary, Cheek's acknowledgement that his failure to file tax returns was based on a belief about constitutionality was viewed by the Supreme Court as possible evidence (1) of Cheek's awareness of the tax law itself (the Court stating that constitutional arguments reveal the taxpayer's "full knowledge of the provisions at issue and a studied conclusion, however wrong, that those provisions are invalid and unenforceable"), and (2) of the voluntary, intentional violation of a known legal duty imposed by the tax law. However, Cheek's statutory argument—his asserted belief that his wages were not income under the statute (the Internal Revenue Code itself)—was ruled by the Supreme Court to be a possible ground for a valid defense even though that belief was not objectively reasonable, provided that the belief was actually held in good faith. The Supreme Court ruled that by instructing the jury that the defendant's statutory argument had to be based on a belief that was "objectively reasonable," the trial judge had erroneously transformed what should have been treated as a factual issue (for the jury to decide) into a legal issue. The Supreme Court stated that whether the defendant acted willfully is a factual issue to be determined by the jury, and that a valid defense of lack of willfulness could be found even though the defendant's belief is not "objectively reasonable." The Supreme Court remanded the case to the trial court for a retrial. The Court also provided guidelines that could be used by the jury at the retrial: Dissent Justice Harry Blackmun, joined by Justice Thurgood Marshall, agreed with the Court's ruling that a