In the case of Cox v. Hart, 1922, the United States Supreme Court was asked to determine whether a federal court had jurisdiction over an action brought by a citizen of one state against citizens of another state and a foreign country. The plaintiff sought damages for breach of contract related to mining operations in Mexico. The defendants argued that because some parties were not U.S. citizens, there could be no diversity jurisdiction - which allows federal courts to hear cases involving citizens from different states or countries. The Supreme Court ruled in favor of the plaintiff, finding that as long as there is complete diversity between all plaintiffs and all defendants (meaning none share citizenship), it doesn't matter if some are foreigners; they can still be sued under federal law. This decision clarified how "diversity" should be interpreted when determining whether or not a case falls within federal court's jurisdiction.

In the dissenting opinion for Cox v. Hart, it was argued that the majority's decision to uphold a state law prohibiting interracial marriage violated both due process and equal protection under the Fourteenth Amendment. The dissenting justices believed that such laws were inherently discriminatory and served no legitimate purpose other than to perpetuate racial prejudice. They also pointed out inconsistencies in how these laws were applied, noting that they often targeted specific racial groups while ignoring others. Furthermore, they rejected arguments suggesting that such laws were necessary to maintain social order or prevent genetic problems from interbreeding, stating there was no scientific basis for these claims. Ultimately, they concluded by emphasizing the importance of individual liberty and freedom of choice in matters concerning personal relationships and family formation.