In the 1972 case Lehnhausen v. Lake Shore Auto Parts Co., the U.S. Supreme Court ruled in favor of Illinois' Director of Department of Local Government Affairs, upholding a state tax law that was challenged by corporations as discriminatory and violating equal protection rights under the Fourteenth Amendment. The law imposed a personal property tax on corporations but exempted individuals from this tax. The court held that states have broad powers to levy taxes and can make distinctions between different types of taxpayers if there is a rational basis for doing so. In this case, it found that Illinois had valid reasons for treating corporate property differently than individual property because corporations benefit more from government services and protections than individuals do.

In the dissenting opinion for Lehnhausen v. Lake Shore Auto Parts Co., Justice Douglas argued that the majority's decision to uphold Illinois' tax classification system was inconsistent with previous rulings on equal protection under the Fourteenth Amendment. He contended that there was no rational basis for treating personal property owned by corporations differently from similar property owned by individuals or partnerships, and thus it violated principles of equality. Furthermore, he criticized the court's deference to state legislatures in matters of taxation as an abdication of its responsibility to enforce constitutional protections against arbitrary discrimination. In his view, this case represented a departure from established jurisprudence and threatened to undermine fundamental rights.