Administrative agencies theoretically are all part of the executive branch of government. We've had administrative agencies and executive departments from the very beginning of the republic since 1789 and the reason is that the President, who is tasked with faithfully executing the law, cannot possibly faithfully execute the law entirely on his own. The President needs assistance and to that end, Congress has established departments and agencies to assist the President in executing the law. But, fundamentally, under our constitutional scheme of separate powers agencies are part of the executive branch assisting in the execution of the law. The very first three executive departments were the departments of foreign affairs of the state, the department of war, and the department of treasury. So, in a sense administrative agencies have been with us since the very beginning, but modern administrative agencies are also different in important respects. Even though administrative agencies are part of the executive branch of government, there are serious questions as to whether administrative agencies or at least some of them are improperly structured in violation of the constitution's provisions for executive power. For example, when agencies make rules and regulations, they are doing so pursuant to delegations of power from Congress, but are there some things that Congress shouldn't be able to delegate? Questions that are too important that the people's representatives should be the ones to decide those questions? Thus when agencies make rules and regulations, there's a question as to whether they're exercising legislative power and legislative power belongs to Congress, not the executive branch. In terms of executive power, the Framers explicitly rejected a plural executive in favor of a unitary executive and they vested all executive power in a single President of the United States. Yet, Congress today sometimes creates independent agencies whose officers are insulated from the President's power to supervise, oversee, and remove them. This raises questions as to whether these independent agencies have recreated a plural executive in violation of the constitutional requirements.