You are still confusing particulars about the US government with universal morality. They are not the same thing. Up until
post 122, we seemed to be talking about universal morality (slavery, moral rights, etc.). And now you switch to US government documents. This brings in a whole new set of definitions for words like “legitimate”. There is “legitimate” in the sense of universal morality, such as when the catechism discusses what a legitimate authority may morally do. And there is “legitimate” in the sense of being in accord with US law and constitution. You cannot use one definition of “legitimate” to support a point about the other sense of the word “legitimate”, and that is exactly what you are trying to do here.
But even that doesn’t work for you because you are choosing which part of the US government to accept (enumerated powers) and which you will reject (the 16th amendment). If you are depending on these documents to give some authority to your argument, you can’t arbitrarily decide to ignore the implications of some of them. But as I said, the approach of using specifics about the US government to support statements of universal morality is fundamentally flawed.
But let’s go back to your statement:
Property has been taken against their will, to benefit someone else. When someone is required to labor and give the fruits of that labor to someone else it is slavery, pure and simple. Authorities do not have a moral leg to stand on.
and combine it with your other statement:
Taxation can legitimately be used to pay for the enumerated powers: courts, defense, etc.
Suppose I have no need of the courts. I have never sued anyone. No one has ever sued me. I have no intention of suing anybody. Yet they take my labor and build a big fancy courthouse, with marble steps and everything. Even if I did see the value in having a court, I might disagree with the expense of making the courthouse with marble steps. So according to your first statement, it is slavery, pure and simple. The authorities do not have a moral leg to stand on. Yet according to your second statement, this is a legitimate use of my taxes. Now I’m really confused!