Why did Antonin Scalia oppose the Independent Counsel Act in Morrison v. Olson?

In Morrison v. Olson (1988), Justice Antonin Scalia issued a lone dissent against the Independent Counsel Act of 1978. His opposition was rooted in his commitment to the separation of powers and the constitutional structure of the executive branch.1

Scalia argued that the Act was unconstitutional because it infringed upon powers that the Constitution provided exclusively to the executive branch. By allowing for the appointment of an independent counsel—an official who operated outside the direct control of the president—to investigate and prosecute executive officials, Scalia believed the law undermined the unitary executive and the system of checks and balances intended by the Framers. For Scalia, this structure was essential to maintaining the limited role of the federal government and ensuring that executive authority remained accountable through the president, rather than being dispersed to unaccountable, court-appointed prosecutors.1