In the case of The Territory of New Mexico v. The United States Trust Company of New York et al., 1898, the Supreme Court was asked to determine whether a territorial government had the authority to tax property owned by non-residents and located within its borders. This arose from an attempt by New Mexico to impose taxes on land grants owned by U.S. Trust Co., which they contested as unconstitutional under equal protection grounds since residents were not similarly taxed. The court ruled in favor of New Mexico, stating that territories have similar powers as states when it comes to taxation and can levy taxes on both resident and non-resident properties within their jurisdiction. They further clarified that while there may be differences in how these taxes are applied (for instance, due to exemptions for certain types or amounts of property), this does not necessarily constitute unequal treatment under law. This decision affirmed the power of territorial governments over matters such as taxation within their jurisdictions - a significant ruling given many western territories' ongoing transition towards statehood during this period.

In the dissenting opinion for The Territory of New Mexico v. The United States Trust Company of New York, Justice Harlan argued that the majority's decision was a misinterpretation of both federal law and the intent behind it. He contended that Congress had not intended to grant territories like New Mexico unrestricted power over their own financial affairs, particularly in relation to issuing bonds. Instead, he believed such powers were meant to be limited and subject to oversight by Congress itself. Furthermore, he disagreed with the majority's view that this case did not involve any constitutional questions; rather, he saw it as fundamentally about whether or not a territory could act beyond its delegated authority without consequence. Ultimately, his concern was that allowing territories unchecked control over their finances would lead them into debt and instability while also undermining congressional authority.