In the Brennan v. Titusville case of 1893, the U.S Supreme Court ruled on a dispute involving property rights and taxation. The city of Titusville in Pennsylvania had imposed taxes on oil tanks owned by Brennan, who argued that these were not taxable as real estate under state law because they could be disassembled and moved. The court disagreed with this argument, ruling that even though the tanks could technically be moved, their fixed nature meant they should still be considered part of the real estate for tax purposes. This decision reinforced local governments' authority to levy taxes on such structures and clarified what constitutes 'real estate' under tax laws.

The dissenting opinion in the Brennan v. Titusville case argued that the majority's decision to uphold a Pennsylvania law prohibiting foreign insurance companies from doing business within its borders was unconstitutional. The dissenters believed this law violated the Commerce Clause of the U.S Constitution, which gives Congress exclusive power over interstate commerce. They contended that insurance is indeed a form of commerce and therefore should be protected under federal jurisdiction, not state laws. Furthermore, they disagreed with the majority's assertion that states have inherent police powers to regulate businesses for public welfare purposes; instead arguing such regulation must still comply with constitutional mandates on interstate trade. This disagreement fundamentally centered around differing interpretations of what constitutes 'commerce' and how far states can go in regulating it without infringing upon federal authority.