Tax Legal Services · Primary-source case analysis

Cheek: A Good-Faith Tax-Law Misunderstanding Can Negate Criminal Willfulness

By Aneeta Mishra and Timothy Chan

Published August 18, 2026 · Updated October 29, 2026

Decision: Cheek v. United States, 498 U.S. 192 (1991).

Does a mistaken belief about tax law differ from deciding not to obey a law you know? That distinction controlled the jury-instruction question in Cheek v. United States. An airline pilot claimed that seminars and his own research led him to believe wages were not taxable. The Supreme Court required the jury to consider a genuinely held misunderstanding of the statutory duty, while rejecting disagreement with the law’s validity as a defense to willfulness. Cheek, 498 U.S. at 194–198, 201–207.

Criminal tax willfulness requires a known legal duty

The government must prove a voluntary, intentional violation of a duty the law imposed and the defendant knew. The requirement responds to the complexity of federal tax obligations.

A claimed misunderstanding is evaluated for actual good faith

The jury could consider whether Cheek actually held his claimed belief, including his awareness of court decisions, IRS rulings, tax forms and instructions. His record included earlier returns, changing withholding claims, civil litigation and advice rejecting his position. The Court did not require the jury to accept his account. It prohibited an instruction that excluded a claimed misunderstanding solely because a judge considered it objectively unreasonable. Cheek, 498 U.S. at 194–195, 202–204.

Constitutional disagreement is different

A person who knows what the tax law requires but believes the requirement is invalid has not misunderstood the duty. Views that the tax statutes are unconstitutional do not negate willfulness under this rule.

The convictions were vacated and the case remanded

On January 8, 1991, the Supreme Court vacated the Seventh Circuit’s judgment and remanded; it did not acquit Cheek or validate his tax positions. The majority decided the challenged objective-reasonableness standard on statutory grounds and did not reach his separate constitutional objections to that standard. The result turns on the criminal willfulness requirement addressed here, not an exemption from paying tax. Cheek, 498 U.S. at 206–207 & n.11.

Justice Scalia agreed that the judgment should be vacated but disagreed with the majority’s treatment of constitutional beliefs. He reasoned that someone who genuinely considers a tax law invalid does not believe it imposes a binding legal duty. Justice Blackmun, joined by Justice Marshall, dissented in the other direction: He viewed the duty to report wages as elementary and feared that the majority’s subjective-belief rule would encourage frivolous tax-protester defenses. The majority’s distinction between misunderstanding a duty and disputing its validity controlled the remand. Cheek, 498 U.S. at 207–210 (separate opinions).

Key takeaways

• Separate misunderstanding of a tax duty from disagreement with a known duty.
• Preserve records showing what the taxpayer was told, read, filed, and understood.
• Evaluate consistency between the claimed belief and the taxpayer’s conduct.
• Do not present Cheek as validating arguments that wages are not income or that the tax laws are unconstitutional.