What is the test for determining whether there is sufficient evidence to convict a person of wilful tax evasion?

The standard of review for assessing the sufficiency of the evidence is whether "after viewing the evidence in the light most favorable to the prosecution, any rational trier of fact could have found the essential elements of the crime beyond a reasonable doubt." United States v. Poschwatta, 829 F.2d 1477, 1481 (9th Cir.1987), cert. denied, 108 S.Ct. 1024 (1988) (citing Jackson v. Virginia, 443 U.S. 307, 319 (1979).

For criminal tax offenses, willfulness means a "voluntary, intentional violation of a known legal duty." United States v. Pomponio, 429 U.S. 10, 12 (1976).