Typically, ignorance of the law is not a defense in our criminal justice system. Under a long-standing legal fiction, defendants are, instead, presumed to know the law. However, the Supreme Court in Cheek v. U.S. established that a lack-of-willfulness defense is generally available in the context of tax law—the so-called Cheek defense. Generally, tax crimes require that a defendant have “willfully” committed the crime. The Cheek defense is applicable when a person is charged with a crime under the Internal Revenue Code.
In order to successfully put forward a Cheek defense, a defendant must have had a good-faith belief that he was not violating the applicable law or statute. The prosecutor must prove that the defendant both knew of the legal duty imposed upon him and that he intentionally violated that duty. The key part of Cheek is that the defendant is held to a subjective standard of what the defendant believed, not what a reasonable person would have believed in the shoes of the defendant. A successful prosecution depends on whether the court and jury determine that the defendant himself had knowledge of the duty and intentionally violated the legal duty regardless of how a reasonable person would have acted.
Throughout the past 25 years, the holding from Cheek has been refined and interpreted by the lower courts. One of the limits to the Cheek defense is that it only applies to federal tax cases that are criminal proceedings. It is important to note that a Cheek defense is not technically a defense because the burden is not on the defendant to prove their good faith belief. The burden is on the prosecutor to prove willfulness—and proving willfulness technically negates a Cheek defense because it demonstrates that the defendant did not have a good faith belief that he was not violating any law or statute.
A defendant seeking to put forward a Cheek defense and to receive a jury instruction to that effect will be required to present some evidence on the issue. Several methods to present evidence exist. The first, but likely more difficult, option is to provide evidence (other than the defendant’s testimony) proving the defendant’s good-faith belief in order to protect the defendant from testifying and being subjected to cross-examination from the prosecutor. In many instances, it might be difficult to locate and provide the evidence exhibiting the defendant’s good-faith belief.
The second option to combat the willfulness element is for the defendant to testify. Defendants must be careful when testifying to support their good-faith belief. By testifying, the defendant waives his Fifth Amendment right not to self-incriminate. If the jury finds that the defendant acted willfully and did not have a good-faith belief, the possibility exists implicitly that a defendant could be viewed as having committed perjury. Perjury occurs when a person gives false testimony concerning a material matter with the willful intent to provide false testimony. Perjury can result in a sentence enhancement if the defendant is convicted. It is also a separate, standalone crime.
The Cheek holding raises another issue that courts and commentators have struggled with—whether willful blindness by a defendant makes the Cheek defense applicable or the defendant’s willful blindness satisfies the “willfull” element of the crime. Willful blindness is the term describing a person who deliberately avoids knowing the law when he should know the law. A willful blindness instruction is used to demonstrate that the defendant acted willfully in avoiding learning the law and thus satisfies the “willfulness” element. The issue is the way a court handles a willful blindness instruction and how the resulting instruction affects a Cheek defense.
Federal circuit courts are divided over the application of a willful blindness instruction, which has led to three varying approaches taken by the courts. Under Ninth Circuit precedent, a willful blindness instruction is appropriate only where a defendant deliberately avoids confirming the existence of a fact they all but knew. A willful blindness instruction is inappropriate when the evidence could justify that the defendant either knew or did not know. Other courts take a different approach. In the First, Third, Eighth, and Eleventh Circuits, the government may use a willful blindness instruction to establish willfulness, and, in doing so, the instruction does not run afoul of Cheek. Other circuits take a different approach. In the Fourth, Fifth, Sixth, Seventh, and Tenth Circuits, a willful blindness instruction applies to a defendant’s knowledge of the law and may establish willfulness. This group of circuit courts does not rely on Cheek to allow a willful blindness instruction, but, instead, the courts focus on whether the defendant’s knowledge of law exists. It does not appear that the Second Circuit or D.C. Circuit have heard a case regarding the relationship between a willful blindness instruction and Cheek.
 U.S. v. Mapelli, 971 F.2d 284, 286 (9th Cir. 1992).
 U.S. v. Anthony, 545 F.3d 60, 64-65 (1st Cir. 2008); U.S. v. Stadtmauer, 620 F.3d 238, 258 (3d Cir. 2010); U.S. v. Dykstra, 991 F.2d 450 (8th Cir. 1993); U.S. v. Dean, 487 F.3d 840, 851 (11th Cir. 2007).
 U.S. v. Martin, 773 F.2d 579, 584 (4th Cir. 1985); U.S. v. Wisenbaker, 14 F.3d 1022, 1027-28 (5th Cir. 1994); U.S. v. Benson, 79 F.App’x 813, 825 (6th Cir. 2003); U.S. v. Hauert, 40 F.3d 197, 203 (7th Cir. 1994); U.S. v. Fingado, 934 F.2d 1163, 1166 (10th Cir. 1991).