Wood v. Wagnon is a landmark Supreme Court case that established the principle of judicial review, which allows courts to determine whether laws passed by state legislatures are constitutional or not. The case involved an appeal from the Kentucky Circuit Court in which James Wood sued William Wagnon for debt collection. In his defense, Wagnon argued that he was protected under a law passed by the Kentucky legislature granting him immunity from debt collection proceedings due to his service as a soldier during the Revolutionary War. The Supreme Court ruled against this argument and held that such legislation violated Article III of the Constitution, which grants Congress exclusive power over military matters and prohibits states from passing any laws related thereto without congressional approval. This ruling set an important precedent establishing judicial review as part of our nation's legal system and ensuring federal supremacy over state governments when it comes to interpreting constitutional rights and obligations.

In Wood v. Wagnon, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by one citizen of Georgia against another in which the plaintiff sought damages for breach of contract. The majority opinion held that it did not have such jurisdiction and dismissed the case. However, Justice Samuel Chase dissented from this decision on two grounds: firstly, he argued that under Article III of the Constitution, federal courts were given exclusive original jurisdiction only over cases between citizens of different states; secondly, he contended that even if there was no constitutional impediment to a state court exercising such power in this instance then it should be allowed to do so as long as its judgment would be respected by other states and enforced within their borders. He concluded his dissent with an assertion that “the right ought never to be denied when justice can be done” and thus urged reversal of the majority's ruling.