In Smoot v. United States (1914), the U.S. Supreme Court ruled on a case involving Reed Smoot, a Mormon senator from Utah who was accused of violating federal law by practicing polygamy. The Senate had previously conducted an investigation into whether Smoot should be allowed to retain his seat due to these allegations and ultimately voted in favor of him remaining in office. However, this decision was challenged and brought before the Supreme Court. The court's ruling upheld the Senate's decision, stating that it had acted within its constitutional authority when determining qualifications for its members beyond those explicitly outlined in the Constitution itself (age, citizenship, inhabitancy). It further stated that any review or reversal of such decisions would infrive upon separation of powers principles as they are inherently non-justiciable political questions meant for Congress alone to decide. This landmark case affirmed legislative autonomy over internal matters while also highlighting complexities surrounding religious freedom versus societal norms and legal standards.

In the dissenting opinion for Smoot v. United States, the justice argued that there was a lack of sufficient evidence to convict Senator Reed Smoot on charges of polygamy and unlawful cohabitation. The justice believed that the majority's decision to expel Smoot from his Senate seat based solely on his affiliation with the Church of Jesus Christ of Latter-Day Saints (LDS) violated principles of religious freedom protected by First Amendment rights. Furthermore, he contended that being a member or even an official in LDS did not automatically imply personal involvement in illegal activities such as polygamy. He also pointed out inconsistencies and contradictions within testimonies used against Smoot during trial proceedings which further cast doubt upon their reliability as substantial proof for conviction.