Martin Neimoeller famously said, of the Nazi government in Germany:

First they came for the socialists, and I did not speak out—because I was not a socialist. Then they came for the trade unionists, and I did not speak out— because I was not a trade unionist. Then they came for the Jews, and I did not speak out—because I was not a Jew. Then they came for me—and there was no one left to speak for me.

Blocking this strategy of coming for one group at a time, with the other groups thinking they are safe until it is too late is a key reason to adhere to John Locke’s principle of insisting the government operate according to established, known laws. He lays out this principle in his 2d Treatise on Government: Of Civil Government, Chapter XI (“Of the Extent of the Legislative Power”), Sections 136 and 137:

 §. 136. Secondly,[3] The legislative, or supreme authority, cannot assume to itself a power to rule by extemporary arbitrary decrees, but is bound to dispense justice, and decide the rights of the subject by promulgated standing laws, and known authorized judges: for the law of nature being unwritten, and so no where to be found but in the minds of men, they who through passion or interest shall miscite, or misapply it, cannot so easily be convinced of their mistake where there is no established judge: and so it serves not, as it ought, to determine the rights, and fence the properties of those that live under it, especially where every one is judge, interpreter, and executioner of it too, and that in his own case: and he that has right on his side, having ordinarily but his own single strength, hath not force enough to defend himself from injuries, or to punish delinquents. To avoid these inconveniences, which disorder men’s properties in the state of nature, men unite into societies, that they may have the united strength of the whole society to secure and defend their properties, and may have standing rules to bound it, by which every one may know what is his. To this end it is that men give up all their natural power to the society which they enter into, and the community put the legislative power into such hands as they think fit, with this trust, that they shall be governed by declared laws, or else their peace, quiet, and property will still be at the same uncertainty, as it was in the state of nature.

§. 137. Absolute arbitrary power, or governing without settled standing laws, can neither of them consist with the ends of society and government, which men would not quit the freedom of the state of nature for, and tie themselves up under, were it not to preserve their lives, liberties and fortunes, and by stated rules of right and property to secure their peace and quiet. It cannot be supposed that they should intend, had they a power so to do, to give any one, or more, an absolute arbitrary power over their persons and estates, and put a force into the magistrate’s hand to execute his unlimited will arbitrarily upon them. This were to put themselves into a worse condition than the state of nature, wherein they had a liberty to defend their right against the injuries of others, and were upon equal terms of force to maintain it, whether invaded by a single man, or many in combination. Whereas by supposing they have given up themselves to the absolute arbitrary power and will of a legislator, they have disarmed themselves, and armed him, to make a prey of them when he pleases; he being in a much worse condition, who is exposed to the arbitrary power of one man, who has the command of 100,000, than he that is exposed to the arbitrary power of 100,000 single men; nobody being secure, that his will, who has such a command, is better than that of other men, though his force be 100,000 times stronger. And therefore, whatever form the commonwealth is under, the ruling power ought to govern by declared and received laws, and not by extemporary dictates and undetermined resolutions: for then mankind will be in a far worse condition than in the state of nature, if they shall have armed one, or a few men with the joint power of a multitude, to force them to obey at pleasure the exorbitant and unlimited decrees of their sudden thoughts, or unrestrained, and till that moment unknown wills, without having any measures set down which may guide and justify their actions: for all the power the government has, being only for the good of the society, as it ought not to be arbitrary and at pleasure, so it ought to be exercised by established and promulgated laws; that both the people may know their duty, and be safe and secure within the limits of the law; and the rulers too kept within their bounds, and not be tempted, by the power they have in their hands, to employ it to such purposes, and by such measures, as they would not have known, and own not willingly.

An established, well-publicized law puts everyone on notice who might be affected by it, and so, if it is a bad law—and sometimes even if it is a good law—can arouse opposition before it is too late. Also, John Locke seems to be arguing that having to work by establishing in advance well-publicized laws will better energize the consciences of rulers—as well as the desire of even powerful rulers to look good, when we writes:

… the rulers too kept within their bounds, and not be tempted, by the power they have in their hands, to employ it to such purposes, and by such measures, as they would not have known, and own not willingly.

A final argument is that, whether a law is just or unjust, the cost of obeying the law will be lower if people can adjust to it:

 … the people may know their duty, and be safe and secure within the limits of the law …

This is a genuine effect, but John Locke does not discuss here the other effect of distortions that might arise from people gaming a law.

John Locke’s footnote within the passage above is closely related to my post “The Only Legitimate Power of Governments is to Articulate the Law of Nature”:

Note 3. Human laws are measures in respect of men whose actions they must direct, howbeit such measures they are as have also their higher rules to be measured by, which rules are two, the law of God, and the law of nature; so that laws human must be made according to the general laws of nature, and without contradiction to any positive law of scripture, otherwise they are ill made. Hooker’s Eccl. Pol. l. iii. sect. 9.
  To constrain men to any thing inconvenient doth seem unreasonable. Ibid. l. i. sect.10.

To me, that is an important message. Too often I here people talking as if a decision arrived at by proper procedure is ipso facto a legitimate decision. But what a government can legitimately do is circumscribed substantively as well as procedurally. Much of the US Constitution is about procedure, but the Bill of Rights is primarily about the substance of what the US government can legitimately do. The rule that laws be established and well-publicized is an important procedural guardrail. But it is not enough by itself.

Here I am drawn to think about administrative law: the administrative procedures law requires justification and a period of public comment for administrative rules. But there should also be substantive limits on what administrative agencies can do. And an important procedural rule for enforcing those substantive limits is the principle of judicial oversight by independently chosen judges. See “People Must Not Be Judges in Their Own Cases.”

For links to other John Locke posts, see these John Locke aggregator posts: 

• John Locke's State of Nature and State of War

• On the Achilles Heel of John Locke's Second Treatise: Slavery and Land Ownership

• John Locke Against Natural Hierarchy