Santa Clara County v. Southern Pacific Railroad Company is a landmark United States Supreme Court case that established the legal principle of corporate personhood. The case arose when the county of Santa Clara, California attempted to impose a tax on the Southern Pacific Railroad Company. The railroad company argued that the tax was unconstitutional, as it violated the Fourteenth Amendment's Equal Protection Clause. The Supreme Court ultimately ruled in favor of the railroad company, holding that the Fourteenth Amendment's Equal Protection Clause applied to corporations as well as individuals. This ruling established the legal principle of corporate personhood, which has been used to extend constitutional rights to corporations. The case has been cited in numerous subsequent Supreme Court decisions, and it remains an important precedent in the area of corporate law.

Justice Field delivered the dissenting opinion in Santa Clara County v. Southern Pacific Railroad Company, arguing that the Court should not have taken jurisdiction of this case and instead should have allowed it to be decided by a lower court. He argued that there was no federal question involved in this dispute between two private parties over taxation, as the Constitution does not grant Congress any power to regulate state taxes or interfere with local matters such as these. Furthermore, he noted that even if there were some constitutional issue at stake here, it would still be inappropriate for the Supreme Court to take jurisdiction since none of its decisions had been challenged on appeal from either party. In conclusion, Justice Field argued that taking up this case was an improper exercise of judicial review and could set a dangerous precedent for future cases involving similar issues.