The case of Montana v. Donald Glenn Imlay, 1992, revolved around the issue of whether a state could impose its own sanctions on an individual for violating federal law when that violation also constituted a breach of state law. The defendant, Donald Glenn Imlay was convicted in Montana for possession and transportation of game animals (elk) taken illegally out-of-state. He argued that he had already been punished under federal law and therefore should not be subject to additional punishment by the State as it violated his Fifth Amendment protection against double jeopardy. However, the Supreme Court ruled unanimously in favor of Montana stating that separate sovereigns - here being Federal Government and State Government - can each enforce their own laws even if those laws prohibit the same conduct.

The dissenting opinion in the case of Montana v. Donald Glenn Imlay argued that the majority's decision to uphold Imlay's conviction for possession of a firearm by a convicted felon was flawed because it failed to consider whether his prior felony convictions were constitutionally valid. The dissent contended that before using these past convictions as grounds for new charges, their validity should have been established beyond doubt. They pointed out that one of Imlay’s previous guilty pleas may not have been made knowingly and voluntarily, which is required under law for such pleas to be considered constitutional. Therefore, they believed this plea could not serve as an adequate basis for his subsequent firearms charge and conviction.