Cheek (D) has been a pilot for American Airlines since 1973. He filed federal income tax returns through 1979 but thereafter ceased to file returns. D claimed an increasing number of withholding allowances - eventually claiming 60 allowances by mid-1980. For the years 1981-1984, he indicated on his W-4 forms that he was exempt from federal income taxes. In 1983, D unsuccessfully sought a refund of all tax withheld by his employer in 1982. D's income during this period at all times far exceeded the minimum necessary to trigger the statutory filing requirement. D was charged with six counts of willfully failing to file a federal income tax return for the years 1980, 1981, and 1983 through 1986, in violation of 26 U.S.C. § 7203. He was further charged with three counts of willfully attempting to evade his income taxes for the years 1980, 1981, and 1983 in violation of 26 U.S.C. § 7201. The tax offenses with which petitioner was charged are specific intent crimes that require D to have acted willfully. Between 1982 and 1986, D was involved in at least four civil cases that challenged various aspects of the federal income tax system. In all four of those cases, the plaintiffs were informed by the courts that many of their arguments, including that they were not taxpayers within the meaning of the tax laws, that wages are not income, that the Sixteenth Amendment does not authorize the imposition of an income tax on individuals, and that the Sixteenth Amendment is unenforceable, were frivolous or had been repeatedly rejected by the courts. D also attended at least two criminal trials of persons charged with tax offenses. There was evidence that, in 1980 or 1981, an attorney had advised D that the courts had rejected as frivolous the claim that wages are not income. D represented himself at trial and testified in his defense. D's defense was that, based on the indoctrination he received from a tax protest group and his own study, he sincerely believed that the tax laws were being unconstitutionally enforced and that his actions during the 1980-1986 period were lawful. He, therefore, argued that he had acted without the willfulness required for conviction of the various offenses with which he was charged. The trial court instructed the jury that, to prove 'willfulness,' the Government must prove the voluntary and intentional violation of a known legal duty, a burden that could not be proved by showing mistake, ignorance, or negligence. The court further advised the jury that an objectively reasonable good-faith misunderstanding of the law would negate willfulness, but mere disagreement with the law would not. The court instructed the jury that, if it found that D 'honestly and reasonably believed that he was not required to pay income taxes or to file tax returns,' a not guilty verdict should be returned. During deliberation, the court further instructed the jury that: 'A person's opinion that the tax laws violate his constitutional rights does not constitute a good faith misunderstanding of the law. Furthermore, a person's disagreement with the government's tax collection systems and policies does not constitute a good faith misunderstanding of the law.' After further deliberation, the District Judge gave the jury an additional instruction. This instruction stated in part that 'an honest but unreasonable belief is not a defense, and does not negate willfulness,' and that 'advice or research resulting in the conclusion that wages of a privately employed person are not income or that the tax laws are unconstitutional is not objectively reasonable, and cannot serve as the basis for a good faith misunderstanding of the law defense.' The court also instructed the jury that 'persistent refusal to acknowledge the law does not constitute a good faith misunderstanding of the law.' The jury returned a verdict finding petitioner guilty on all counts. D appealed his convictions, arguing that the District Court erred by instructing the jury that only an objectively reasonable misunderstanding of the law negates the statutory willfulness requirement. The United States Court of Appeals for the Seventh Circuit rejected that contention and affirmed the convictions. The Supreme Court granted certiorari.