"Proper", "Plenary", and Preamble

It was not until NFIB v. Sibelius, 132 S.Ct. 2566 (2012), that the Supreme Court began to address the meaning of "proper" in the Necessary and Proper Clause, on which most of the powers of government have been erected since the breakthrough case of McCulloch v. Maryland, 17 U.S. (4 Wheat.) 316 (1819), in which CJ John Marshall interpreted "necessary" to mean "convenient", and said nothing about "proper". It and Sibelius also did not address the meaning of "carrying into execution", discussed elsewhere (see links at the end).

Ilya Somin has an article on this, The Individual Mandate and the Proper Meaning of “Proper” at SSRN. He explains that five of the justices agreed that "proper" does not allow "plenary" (unlimited) power, but they did not offer clear guidance on where the boundaries are.

CJ Marshall also introduced the term "plenary" into Supreme Court jurisprudence in Gibbons v. Ogden, 22 U.S. 1 (1824), in which he found that delegations of power were "plenary" within their sphere (subject matter). Ever since government lawyers have been building power on that opinion.

It requires only a little research into the historical background of legal delegation of power, and usage of the term "plenary", to find that no delegations of constitutional power can ever be literally unlimited, that is, "plenary". There is always an implicit constraint that a power only be exercised for a legitimate public purpose, and that is what the Framers meant by "proper", not just for incidental "necessary and proper" powers, but all powers.

So where can we find authoritative guidance for what is proper? We can go back to Edward Coke, William Blackstone, and other legal authorities on whom the Founders relied, but we can also find a large part of it in the Constitution itself, indeed at the very beginning of it, the Preamble:

We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.

Now the conventional view that that the Preamble adds no real content to the Constitution. It is merely what lawyers call "aspirational". It delegates no powers, defines no rights or duties, creates no structures or procedures. But it is not without constitutional meaning, because it defines six constraints on what are legitimate exercises of power, and therefore on delegations of power. Those are not the only constraints, but it is a good start.

Let us consider some delegations of power in the Constitution, and consider what it would mean if the delegations were "plenary":

Art. I Sec. 4 Cl. 4. The Times, Places and Manner of holding Elections for Senators and Representatives, shall be prescribed in each State by the Legislature thereof; but the Congress may at any time by Law make or alter such Regulations, except as to the Places of chusing Senators.

If the pre-emptive power of Congress over the time, place, and manner of congressional elections (except the place of senatorial elections) were plenary, they could require the elections be held within a 1-second timeframe, at a polling place on the moon, while standing on one's head. Ridiculous? Of course. The power may only properly be exercised to make elections more accurate, convenient, and representative. That is an implied restriction on the delegation, which is not made explicit in the Preamble, but may be expressed as being for a "legitimate public purpose".

Or consider this:

Art. I Sec. 8 Cl. "The Congress shall have power ... To provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress;

If that congressional power were plenary, it would seem to allow Congress to forbid militia training and assembly or action. But that would be in conflict with the preamble of the Second Amendment:

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

Which clearly implies the intent that militia be kept in a high state of readiness. A proper exercise of the power would be to enhance the effectiveness of militia, not impair it. It may be regulated, but only in one direction.

Here is another that some lawyers have been arguing is plenary:

Art. IV Sec. 3 Cl. 2. The Congress shall have Power to dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States; ...

They actually argue this clause confers plenary, unlimited, power to dispose of any property in any way Congress may choose, even to drain the treasury to give all public funds to themselves or their cronies (which seems to be what they are doing), or to give any or all of the land of the country to a foreign enemy to be used to attack us. That obviously can't be correct. In fact the power is that of a fiduciary, with government officials acting as trustees of the trust defined by the Constitution, having the duty to manage public trust assets for the general benefit of the people as a whole, not for the special benefit of a part of the people.

We also see this indicated in

Art. I Sec. 8 Cl. 1. The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; 

In this clause, "common defense and general welfare" are not distinct delegations of power, but restrictions on the purposes of taxing and spending, that they be for the general benefit of all and not for the special benefit of a few.

Improper exercises of power are also what give rise to complaints of "abuse of discretion", which are in principle justiciable. If the powers of officials were plenary there could be no abuse of discretion.

Proposed amendment

No plenary powers
All powers delegated in this Constitution are constrained to be exercised only for a proper, or reasonable, rational, and legitimate, public purpose, as a fiduciary trust for the general benefit of all the people and not for the special benefit of any part of them, partially but not completely stated in the Preamble. No power is plenary or without limits, and no power may be extended to accomplish a purpose without amendment.

See also:

1. Ratchet of rot
2. Unnecessary and Improper — Analysis of Necessary and Proper Clause.
3. The original meaning of "carrying into execution" — The restrictive phrase has never been properly adjudicated.
4. Diagram of Necessary and Proper Clause