In the 1962 case of Baker v. United States, the Supreme Court ruled on a matter concerning federal jurisdiction over crimes committed on Native American reservations. The defendant, an enrolled member of the Oglala Sioux Tribe, was charged with involuntary manslaughter after killing another tribal member in a car accident within reservation boundaries. He argued that since both parties were members of the same tribe and the incident occurred on tribal land, it should be handled by tribal courts rather than federal ones. However, under Major Crimes Act (1885), certain major crimes committed by Native Americans in "Indian Country" fall under federal jurisdiction regardless of victim's identity or offender’s affiliation to any tribe. The court held that Congress has plenary power over Indian affairs and can thus determine which judicial body has authority over such cases; this includes granting jurisdiction to Federal courts for serious offenses like manslaughter even if they occur between two Indians on a reservation. Therefore, despite being tried in Federal court instead of Tribal court as he desired - Mr.Baker's conviction was upheld.

The dissenting opinion in the Baker v. United States case argued that the majority's decision to uphold a conviction for tax evasion was incorrect because it relied on an overly broad interpretation of "willfulness." The dissent contended that willful intent should be defined more narrowly, requiring proof of specific intent to evade taxes rather than just general knowledge of wrongdoing. They believed this broader definition could potentially criminalize innocent mistakes or negligence, which is not consistent with traditional principles of criminal law. Furthermore, they disagreed with the majority's assertion that ignorance of the law is no excuse; while generally true in most areas of law, they felt there should be exceptions for complex laws such as those governing taxation where even well-intentioned individuals can easily make errors due to their complexity and frequent changes. Thus, by upholding this conviction without clear evidence demonstrating specific intent to defraud the government out its lawful revenue through deceitful or dishonest means would set a dangerous precedent.