The U.S. Supreme Court case Hellmich, Collector v. Missouri Pacific Railroad Company in 1926 revolved around the issue of taxation on railroad property and whether it violated the Fourteenth Amendment's Equal Protection Clause. The Missouri Pacific Railroad Company sued George E. Hellmich, a tax collector for St. Louis County, arguing that their property was being assessed at a higher rate than other properties within the county - an act they claimed to be discriminatory and unconstitutional under state law as well as the Fourteenth Amendment of U.S Constitution which guarantees equal protection under law to all citizens. However, after reviewing evidence presented by both parties including assessment ratios for different types of properties across several years, the court ruled against Missouri Pacific Railroad Company stating that there was no clear proof showing intentional or systematic discrimination against them by tax authorities. Furthermore, while acknowledging some inconsistencies in assessments between different classes of property due to human error or judgement differences among assessors over time; these were not deemed sufficient enough to constitute violation of constitutional rights warranting judicial interference with state’s taxing power.

In the dissenting opinion for Hellmich, Collector v. Missouri Pacific Railroad Company, it was argued that the majority's interpretation of the law was incorrect and overly broad. The dissent contended that a tax on gross receipts from interstate commerce is not necessarily an unconstitutional burden on such commerce. It emphasized that while taxes can be burdensome if they are excessive or discriminatory, there is no inherent constitutional issue with taxing gross receipts from interstate commerce as long as these conditions aren't met. Furthermore, it pointed out inconsistencies in previous rulings by the court regarding this matter and urged for a more nuanced understanding of what constitutes an undue burden on interstate commerce.