T he Constitution neither establishes administrative agencies nor explicitly prescribes the manner by which they may be created. Even so, the Supreme Court has generally recognized that Congress has broad constitutional authority over the establishment and shape of the federal bureaucracy. This power stems principally from the combination of Congress's enumerated powers under Article I of the Constitution to legislate on various matters; language in Article II, Section 2, which authorizes the appointment of "officers" to positions "which shall be established by law"; and Article I, Section 8, which authorizes Congress to "make all laws which shall be necessary and proper for carrying into execution" not only Congress's own enumerated powers, but "all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof." Acting pursuant to its broad constitutional authority, Congress may create federal agencies and individual offices within those agencies, design agencies' basic structures and operations, and prescribe, subject to certain constitutional limitations, how those holding such offices are appointed and removed. Congress also may enumerate the powers, duties, and functions to be exercised by agencies, as well as directly counteract, through later legislation, certain agency actions implementing delegated authority. The most potent tools of congressional control over executive branch agencies, including structuring, empowering, regulating, and funding agencies, typically require enactment of legislation. Such legislation must comport with the constitutional requirements of bicameralism (i.e., it must be approved by both houses of Congress) and presentment (i.e., it must be presented to the President for signature). For legislation to take effect, that constitutional process requires the support of the House, Senate, and the President, unless the support in both houses is sufficient to override the President's veto. But Congress does not always need to act through legislation to impact agency decisionmaking. Several tools available to the House, Senate, congressional committees, and even individual Members of Congress may be employed to influence agency action. Some tools are explicitly enumerated in the Constitution, such as impeachment and subsequent removal from office, and Senate advice and consent to the ratification of treaties and the appointment of certain executive officers, ambassadors, and judges. Under these provisions, the Constitution has explicitly authorized an individual house of Congress to act unilaterally with binding legal effect. Other tools, however, are both non-constitutional (i.e., they are not explicitly established in the Constitution) and non-statutory (i.e., they do not require enactment of legislation). Most of these non-constitutional, non-statutory tools, while capable of influencing agency decisionmaking, cannot themselves legally compel agency action. This distinction between the compulsory nature of statutory enactments and the non-binding nature of most (though not all) non-statutory legislative actions is essential to understanding the scope of congressional authority over federal agencies. Congress's power to create agencies is well established. Members of the First Congress viewed the Constitution as contemplating the creation of "departments of an executive nature" to "aid" the President in the execution of law. Toward this end, the First Congress enacted measures creating the Departments of Foreign Affairs, Treasury, and War. At this early stage, Congress sought to ensure it retained some degree of influence and control over the new departments. The Secretary of the Treasury, for example, had to report directly to Congress, either "in person or in writing," on "all matters referred to him by the Senate or the House." Yet the debates of the First Congress also provide evidence of Congress's acknowledgment of what would become the delicate, and at times uneasy, balance between congressional creation and control of agencies and the President's authority to supervise executive officials pursuant to his constitutional obligation to "Take Care that the laws be faithfully executed." From the very outset, Congress wrestled with defining the scope of both presidential and congressional control of executive agencies. For example, in 1789 Congress engaged in a historically significant debate on the President's authority to remove the Secretary of Foreign Affairs. Although Members' views differed, ultimately the prevailing position was "in favor of declaring the power of removal to be in the President," rather than in the Congress. Similarly, a proposal to structure the Department of the Treasury as a multi-member commission, partly to insulate the agency from presidential control, was debated and eventually rejected out of concern that such a body would not be able to administer effectively the finances of the new government. As reflected in the debates of the First Congress and confirmed by later Supreme Court decisions, Congress's power over the administrative state, though broad, is not unlimited. In particular, constraints on congressional power over executive agencies flow from the foundational constitutional doctrine of the separation of powers. Although the text of the Constitution distributes the legislative, executive, and judicial powers among the three branches of government, the Supreme Court has not endorsed any absolute separation. The allocation of powers was never intended, in the words of Justice Oliver Wendell Holmes, to cause the branches to be "hermetically sealed," or divided into "fields of black and white." Instead, observed Justice Robert Jackson, the separation of powers "enjoins upon [the] branches separateness but interdependence, autonomy but reciprocity." It is a doctrine generally characterized by ambiguity and overlap rather than bright-line rules. Yet some well-established principles govern the relationship between Congress and the administrative state. For example, Congress may neither displace executive authority by directly implementing the law itself, nor appoint or reserve for itself the power to remove (except through impeachment) executive officers engaged in the execution of law. On the other end of the spectrum, the separation of powers is not violated merely by Congress directing, prohibiting, or otherwise legislating on most forms of agency action. It would appear that the chief substantive limitations on Congress's ability to control the executive branch arise from specific constitutional provisions and implied principles—intimately connected to the separation of powers—that buttress the general division of power among the branches. These provisions and principles, which include the Appointments Clause, the Take Care Clause, and the President's authority to supervise the executive branch, are addressed below in conjunction with Congress's statutory powers. Congress's ability to control administrative agencies through the exercise of legislative power is a holistic endeavor perhaps best understood as built upon four basic pillars: structural design, delegation of authority, procedural controls on agency decisionmaking, and agency funding. Reliance on each pillar, however, is informed by separation-of-powers principles. How an agency is structured invariably affects how it operates, and what sort of relationship it has with the Congress and the President. In creating a federal agency, Congress may structure or design the agency in several ways. Many of Congress's structural choices affect the independence of agencies by shaping the degree to which the President can assert control over them. These structural choices are wide-ranging, but generally relate to agency leadership, appointment and removal of officers, and presidential supervision. For example, subject to constitutional considerations explained below, Congress may structure agency leadership in the form of a multi-member commission or a single director; create agency offices, which may be filled by persons appointed by the President with the advice and consent of the Senate, or in the case of "inferior" offices, vest the power of appointment in the President, the head of a department, or the "Courts of Law"; establish certain statutory qualifications for appointees, often based on political affiliation or substantive experience, or dictate the length of an official's term of office; choose to make an agency freestanding, or place it within an existing department or agency; provide that an agency official serve at the pleasure of the President, or, in certain situations, be protected from removal except in cases of "inefficiency, neglect of duty, or malfeasance in office"; or choose to exempt an agency from certain aspects of presidential supervision—for example by excusing the agency from complying with generally applicable executive branch requirements that agency rules, legislative submissions, and budget requests be reviewed and cleared by the White House. Although Congress may wish to insulate an agency from presidential control through these structural choices, fundamental constitutional requirements must be complied with in designing federal agencies. These limits, two of which are discussed below, generally exist to ensure that executive branch officials remain accountable to the President, and ultimately the public, for their actions. The Appointments Clause imposes significant limitations on the structural choices that Congress may make in determining how executive agency officials are appointed. Under the Clause, principal officers must be appointed by the President, "with the Advice and Consent of the Senate," while Congress may vest the appointment of "inferior Officers" "in the President alone, in the Courts of Law, or in the Heads of Departments." Non-officers—that is, "mere employees"—are not subject to any constitutionally required method of appointment. The breadth of authority that an executive branch official exercises typically determines the official's classification as either an officer or non-officer for Appointments Clause purposes. Generally, if an executive official holds a "continuing position established by law" and "exercis[es] significant authority pursuant to the laws of the United States," he is an "Officer of the United States." The applicable standard for distinguishing between principal officers—who must be appointed with the advice and consent of the Senate—and inferior officers—whose appointment Congress may vest elsewhere—is arguably less clear. At times, the Supreme Court has adopted an approach that suggests the distinction between a principal and inferior officer hinges mainly on whether the officer is subject to supervision by some higher official, and not on the amount of overall authority exercised. Under this approach, principal officers are generally subject only to supervision by the President, while inferior officers are generally subject to supervision by a higher-ranking, Senate-confirmed official. Thus, in designing agencies, Congress generally has little discretion in directing the method of appointment for most agency heads.