In the United States v. Eaton case of 1897, the U.S. Supreme Court ruled on a matter concerning temporary appointments to public offices under the Constitution's Appointments Clause. The issue arose when John Eaton, who was serving as vice consul in Bangkok, assumed duties of Consul General after his superior fell ill and subsequently died while on leave for health reasons. Upon returning to America, he sought compensation for performing those additional responsibilities but was denied by accounting officers of the Treasury Department because he had not been officially appointed or confirmed by Senate as required by law. The court held that an individual could temporarily perform higher-level duties without official appointment if it is "actual and urgent necessity" due to unforeseen circumstances such as illness or absence of superiors; this would not violate constitutional requirements regarding office appointments. Therefore, Eaton should be compensated accordingly for his services rendered during that period.

In the dissenting opinion for United States v. Eaton, Justice Harlan disagreed with the majority's interpretation of the Consular Act of 1856. He argued that this law did not give consuls general or commercial agents any authority to perform diplomatic functions in a foreign country when there was no minister resident or consul present. According to him, such an interpretation would allow these officials to exercise powers they were never intended to have and could potentially lead to abuses. Furthermore, he contended that if Congress had wanted these officials to be able to act as chargé d'affaires ad interim under certain circumstances, it would have explicitly stated so in the legislation. Therefore, he believed that Mr.Eaton should not have been allowed by law or precedent from performing duties beyond his role as a consul-general during his time in Siam (now Thailand).