What, Legally, Justifies Eminent Domain?

Question

In the United States, under the Taking Clause of the Fifth Amendment, the Federal Government's power of Eminent Domain is established:

nor shall private property be taken for public use, without just compensation.

Therefore, even in a case where the use of Eminent Domain went against the expressed wishes of a given State, so long as it was "justly compensated" the Federal Government has full legal authority of the claiming of land.

My question is: why? I know arguments about public necessity, and the origins of the practice in English Common Law, but what I'm looking for, is twofold:

1. Where in the Constitution is it stated the Federal Government has full legal jurisdiction over all State land?
2. Is this interpretation (that the Federal Government has complete control over State land) actually correct?

Answer 1

Article I, Section 8 of the United States lists the powers of Congress (and a handful a sprinkled elsewhere in the U.S. Constitution and its amendments, such as the power to regulate court jurisdiction in Article III and the enforcement powers of the 13th and 14th Amendments, to give a non-exclusive list).

These powers include powers reasonable and necessary to achieve the other powers.

Various federal statutes authorize eminent domain power exercises in different contexts for different purposes expressly set forth in those statutes and the constitution.

The Supremacy Clause of the United States Constitution (Article VI, Clause 2) makes federal law supreme over state law in every state. It states:

This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.

The federal government has control over everything happening in U.S. states to the extent that it is in furtherance of the limited powers of the federal government set forth in the constitution, and not in violation of any prohibition on federal action in that area (e.g. the federal government can bribe state governments but cannot generally force them to take a particular action on its behalf).

Answer 2

The Federal Government does not have full legal jurisdiction. You're mistakenly assuming it has.

The problem is that governments (federal and state) can act as private parties in certain cases. In particular, they can be owners. The Eminent Domain principle allows the Federal government to take ownership, yes, but ownership does not give full legal jurisdiction. In particular, it's not a way around the Tenth Amendment. Ownership of land gives the rights and responsibilities as dictated by State law.

Answer 3

1) See your quoted text.

2) No, it doesn't say it has complete control over state land. Then again, state land is not private land, anyway.