[4] John Cheek himself was eventually charged with six counts of willfully failing to file Federal income tax returns under 26 U.S.C.

[6][7] He also testified that around 1978 he had begun attending seminars conducted by a group that believed that the Federal income tax system was unconstitutional.

Cheek specifically testified about his own interpretations of the U.S. Constitution, court opinions, common law and other materials.

Cheek also contended that his wages from a private employer (American Airlines) did not constitute income under the internal revenue laws.

Some U.S. criminal statutes provide for what are known as "specific intent" crimes, where ignorance of the law may be a valid defense.

The trial court also instructed the jury that "[a]dvice 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.

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"),[21] and (2) of the voluntary, intentional violation of a known legal duty imposed by the tax law.

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 Court also provided guidelines that could be used by the jury at the retrial: [...] in deciding whether to credit Cheek's good-faith belief claim, the jury would be free to consider any admissible evidence from any source showing that Cheek was aware of his duty to file a return and to treat wages as income, including evidence showing his awareness of the relevant provisions of the Code or regulations, of court decisions rejecting his interpretation of the tax law, of authoritative rulings of the Internal Revenue Service, or of any contents of the personal income tax return forms and accompanying instructions that made it plain that wages should be returned as income.

These two justices complained, however, about the Court's ruling that a genuine, good faith belief based on a misunderstanding of the Internal Revenue Code is a valid defense.

[...] [I]t is incomprehensible to me how, in this day, more than 70 years after the institution of our present federal income tax system with the passage of the Revenue Act of 1913, 38 Stat.

[23] In addition, attorney Daniel B. Evans points out that the Cheek defense is logically self-defeating: ...[I]f you plan ahead to use it, then it is almost certain to fail, because your efforts to establish your "good faith belief" are going to be used by the government as evidence that you knew that what you were doing was wrong when you did it, which is why you worked to set up a defense in advance.

[24] In the case of John Cheek: The 48-year-old airline pilot said in a telephone interview that he had changed his views about paying taxes and was now "straightened out with the I.R.S."