The U.S. Supreme Court case Phillip Wagner, Incorporated v. Leser et al., Judges and Tax Collector of Baltimore City in 1915 revolved around the issue of taxation on out-of-state corporations operating within Maryland state lines. The plaintiff, Phillip Wagner Inc., an Ohio-based corporation that sold beer in Maryland, argued against a law requiring foreign corporations to pay taxes for doing business in the state while exempting domestic companies from such obligations. They claimed this was discriminatory and violated both the Fourteenth Amendment's Equal Protection Clause and Article I Section 8's Commerce Clause of the Constitution. However, the court ruled against them stating that states have broad powers to tax businesses within their borders as long as it does not interfere with interstate commerce or discriminate between different types of property or classes of property owners. It held that since all corporations were taxed equally under Maryland law regardless if they were domestic or foreign entities - there was no violation either constitutionally protected rights.

In the dissenting opinion for Phillip Wagner, Incorporated v. Leser et al., Judges and Tax Collector of Baltimore City, it was argued that the Maryland law in question did not violate the Fourteenth Amendment's Equal Protection Clause. The dissenting justices believed that there was a rational basis for treating corporations differently from individuals when it came to taxation. They contended that corporations enjoy certain benefits and protections under state laws which justify higher tax rates compared to individual taxpayers. Furthermore, they disagreed with the majority's interpretation of "property" under Maryland law, arguing instead that corporate shares should be considered as separate entities distinct from their underlying assets for taxation purposes.