In the case of Mandelbaum v. United States, 1925, the U.S Supreme Court upheld a conviction for conspiracy to defraud the government by manipulating sugar prices during World War I. The defendants were charged with conspiring to fraudulently manipulate and control the price of refined sugar in violation of Section 37 of the Criminal Code. They appealed their convictions arguing that they had not committed any crime because there was no law regulating sugar prices at that time. However, Justice Oliver Wendell Holmes Jr., writing for a unanimous court, rejected this argument stating that even though there was no specific law against what they did, it still constituted an illegal conspiracy under common law principles because it involved deceitful practices intended to cheat or deceive others which is inherently unlawful.

In the dissenting opinion for Mandelbaum v. United States, Justice Oliver Wendell Holmes Jr. disagreed with the majority's decision to uphold a conviction based on circumstantial evidence of intent to defraud in a mail fraud case. He argued that there was insufficient direct evidence linking the defendant to fraudulent activities and that mere possession of materials used in such activities did not necessarily imply guilt. Furthermore, he contended that it was inappropriate for courts to infer criminal intent from ambiguous circumstances without clear proof of wrongdoing. This could potentially lead to wrongful convictions based on conjecture rather than concrete evidence, undermining principles of justice and fairness underpinning American law.