Poindexter v. Greenhow, Treasurer was a United States Supreme Court case that dealt with the issue of whether a state could tax the income of a federal officer. The case was brought by William Poindexter, a federal officer, who was being taxed by the state of Virginia on his income. Poindexter argued that the state of Virginia had no right to tax his income, as it was a federal officer. The Supreme Court ultimately sided with Poindexter, ruling that the state of Virginia had no right to tax the income of a federal officer. The Court reasoned that the federal government had exclusive authority over the salaries of its officers, and that the state of Virginia had no right to interfere with this authority. The Court also noted that the state of Virginia had no power to tax the income of a federal officer, as this would be a violation of the Supremacy Clause of the United States Constitution. In conclusion, the Supreme Court ruled in favor of Poindexter, finding that the state of Virginia had no right to tax the income of a federal officer. This ruling established the principle that the federal government has exclusive authority over the salaries of its officers, and that the states cannot interfere with this authority.

Justice Field delivered the dissenting opinion in Poindexter v. Greenhow, Treasurer. He argued that the majority had erred by failing to consider whether or not a state could be held liable for damages caused by its officers acting outside of their authority and beyond the scope of their duties. In this case, Virginia had passed a law authorizing its treasurer to invest public funds in certain bonds issued by private companies; however, when he invested those funds into other securities without authorization from the legislature, it resulted in losses for which Virginia was being sued. Justice Field maintained that since there was no precedent on point as to whether states can be held responsible for such actions taken by their agents and officers, it should have been left open until further consideration could be given to all relevant factors involved. Furthermore, he noted that if states were allowed immunity from liability under these circumstances then they would essentially become unaccountable for any wrongs committed while carrying out official business - something which would undermine justice and lead to an unjust result overall.