The latest contribution is from Emily Bremer, The Unwritten Constitution of the Fourth Branch:
It is widely accepted that the powers of the federal government flow from the U.S. Constitution. Yet in practice, most federal power is exercised through administrative agencies, institutions not mentioned in the Constitution. Since the New Deal era, administrative law — the seemingly disparate set of rules governing agency action that are found in statutes, judicial decisions, and executive directives — has accommodated the emergence of this fourth branch of government not contemplated by the framers. Familiar principles, including the separation of powers, the rule of law, and individual liberties, permeate administrative law. But these principles cannot expressly be located in the U.S. Constitution. So what is their legal and theoretical foundation? And how are they found in administrative law?From the closing paragraphs: "Over the course of nearly a century of development, administrative law has thus evolved to accommodate the administrative state, filling the Constitution's silence with an unwritten constitution of the fourth branch - a body of seemingly disparate rules that extends a uniform and recognizable set of substantive constitutional values into the modern administrative context".
This Article argues that administrative law provides an unwritten constitution for the fourth branch. American administrative law is illuminated law through the lens of constitutional theory, and particularly principles of British constitutionalism. This Article shows that administrative law rules, though not formally entrenched, perform essential constitutional functions where the written Constitution has little or no application. These functions include constituting government agencies, determining institutional boundaries, establishing the government-citizen relationship, and protecting fundamental values.
The unwritten constitution theory provides a legal and theoretical foundation for ensuring that the administrative state operates consistently with constitutional principles. It also legitimates administrative common law and illuminates political obligations to respect constitutional principles in administrative law development and reform.
The paper is well worth a read. I think American scholars may be guilty of overthinking the problem of the legitimacy of the general principles of judicial review. After all, the general framework provided by the Administrative Procedure Act is open-ended and requires interpretation. But they are quite right to focus on the values that are informing this interpretation and ask what they contribute to the legitimacy of the administrative state.