In the United States v. Lombardo case of 1915, the Supreme Court ruled that an individual could not be deported based on their beliefs or associations unless they were actively engaged in illegal activities. The case involved a man named Andrea Lombardo who was ordered to be deported because he was a member of the Industrial Workers of the World (IWW), which at that time was considered by many as an anarchist organization. However, there wasn't any evidence showing that Lombardo had participated in any unlawful actions himself. The court held that mere membership in such an organization did not constitute grounds for deportation under immigration laws then existing, and thus overturned his deportation order.

In the dissenting opinion for United States v. Lombardo, Justice Holmes disagreed with the majority's interpretation of conspiracy law. He argued that a conspiracy could not be formed without an illegal act being committed or at least planned to be committed by two or more people. In this case, he believed that there was no evidence presented showing any agreement between Lombardo and others to commit an unlawful act against U.S immigration laws. Therefore, in his view, merely helping immigrants evade authorities did not constitute a criminal conspiracy unless it involved some form of deceitful conduct intended to violate those laws directly. Furthermore, he contended that if every person who gave advice about evading legal consequences were deemed conspirators under federal law then many lawyers would find themselves guilty as charged which is absurd and unjustifiable from both legal and moral perspectives.