We find the statement to be so self-evident that we mostly do not discuss it, that the Government should not be capricious and arbitrary. We talk about the Rule of Law, and Equality Under the Law. But what do these really mean? They are all premised on this point: Just as the Moral Law affects us as individuals, so it should (must) influence Government and how Government interacts with the People.
If Government is to govern all the people, it must have a consistent standard to apply to all the people. It must, in short, have some form of Morality. This Morality would inform not just the civil and criminal legal code, but also the decisions made by the government in how to enforce those codes. It would influence what areas of life the Government would leave alone, and those in which it would take an interest. And, here, we must decide what form of Morality it should choose.
If it chooses to follow the Universal Moral Law, as we have discussed, then we know that the same rules that constrain our behavior, and that inform our policy would also constrain the Government's behavior and inform it's policies. If the Government is constrained by the Universal Moral Law, it is held to the same standards of justice, compassion, and responsibility as we are individually. It must consider what it does in light of all the people- knowing that any group which is arbitrarily benefited will necessarily harm some other group- and that is not just. It would know that spending money it doesn't have, and raising taxes to punitive levels is neither compassionate, nor just. But, because the Universal Moral law is not exactly the same as the Religious Law, it also knows that requiring, or promoting, any specific religion also fails to be just, compassionate, or responsible.
It is because of this that we have no reason to fear a Theocracy in America. It is because of this that we can be comfortable "Legislating Morality." A Government acting as though it is constrained by the Moral Law is one that we have no reason to fear. It won't make the "disputable" thing illegal- because it knows it has no Moral Authority to do so. It won't make arbitrary decisions- because such would be immoral.
Now, obviously, our current Government does not operate that way very well. Largely this is because we have ceased expecting our Representatives to be Moral People. More specifically, the Democrats have rejected the Moral Law in favor "what feels good" and selfishness. But, even here, the Moral Law speaks. It says that such blatant immorality should be forcefully opposed. If we required Conservative politicians to be as Moral as we are, they would find the over-reach by Liberals so immoral, so heinous, that they would not submit to merely "moral" victories. They would oppose the advance of Liberalism with every fiber of their being.