In the case of Federal Power Commission v. Florida Power & Light Co., 1971, the U.S Supreme Court ruled in favor of the Federal Power Commission (FPC). The issue at hand was whether or not FPC had jurisdiction over wholesale sales from a power company's system that included both licensed and unlicensed facilities. Florida Power & Light argued that such sales were outside FPC’s authority because they involved energy produced by non-federally regulated plants. However, the court held that if any part of an interconnected and coordinated electric system is subject to federal licensing, then all wholesale rates for electricity sold through this integrated network fall under FPC’s jurisdiction regardless of where it originated within said network. This decision affirmed FPC's ability to regulate interstate electricity transactions comprehensively.

In the dissenting opinion for Federal Power Commission v. Florida Power & Light Co., Justice Douglas argued that the majority's decision to uphold the Federal Power Commission's (FPC) authority over wholesale electricity rates was a misinterpretation of the Federal Power Act. He contended that Congress intended to give FPC jurisdiction only over interstate transactions, not intrastate ones, and thus it should not have authority over Florida’s power company which operates solely within state lines. He also expressed concern about federal intrusion into areas traditionally regulated by states and warned against expanding federal powers at the expense of state sovereignty. Furthermore, he disagreed with how FPC calculated costs in setting rates, arguing they should consider future as well as past investments made by utilities companies.