Is an employee's duty to disclose material information to his employer imposed by state or federal legislation?

Our discussion is not to be construed as holding that an employee's duty to disclose material information to his employer must be imposed by state or federal statute. Indeed, the employment relationship, by itself, may oblige an employee not to conceal, and in fact to reveal, information he has reason to believe is material to the conduct of his employer's business. See United States v. Brown, 540 F.2d 364 (8th Cir. 1976); United States v. Groves, 122 F.2d 87 (2d Cir.), cert. denied, 314 U.S. 670, 62 S.Ct. 135, 86 L.Ed. 536 (1941).