The U.S. Supreme Court case County of Yakima, et al. v. Confederated Tribes and Bands of the Yakima Indian Nation in 1991 revolved around a dispute over land taxation rights within reservation boundaries. The county had imposed ad valorem taxes on allotted lands held by tribal members and sold certain parcels to satisfy unpaid tax debts without federal approval, which the tribe argued was unlawful under Section Six of the General Allotment Act (GAA) that prohibited such actions without Congressional consent. However, the court ruled in favor of Yakima County with a 6-3 decision stating that while Section Five forbade state taxation on allotted lands still held in trust by Federal Government for Native Americans, it did not extend this prohibition to fee-patented lands - those transferred into private ownership after allotment period ended - thus allowing local governments to impose property taxes on them.

In the dissenting opinion for County of Yakima, et al. v. Confederated Tribes and Bands of the Yakima Indian Nation, Justice Blackmun argued that the majority misinterpreted both federal law and precedent in its decision to allow Yakima County to impose an ad valorem tax on reservation land owned by tribal members. He contended that such a tax was not explicitly authorized by Congress under Section 6 of the General Allotment Act (GAA), which only permitted taxation upon "alienation" or transferal of property ownership - something that had not occurred in this case. Furthermore, he pointed out inconsistencies between this ruling and previous cases where similar taxes were deemed unlawful without explicit congressional approval. Finally, he expressed concern about potential negative impacts on Native American self-governance and economic development resulting from allowing local governments to unilaterally impose taxes on reservation lands.