This is an article that I wrote so time ago that applies to the Oregon issue today. Does the Constitution allow the Federal Government to own State land?
The Constitution does not grant the federal government the right or authority to arbitrarily take, control, or own any State lands. Congress may exercise exclusive legislative “authority over all places purchased by the consent of the legislature of the state in which the same shall be, for the erection of forts, magazines, arsenals, dockyards, and other needful buildings;” in other words, ‘Must’ obtain permission from the State to acquire property within that State.
Does the Constitution Grant the Federal Government the Power to Legislate over Land within the Several States? http://www.thepriceofliberty.org/06/02/06/greenslade.htm
Federal Acquisition of Land Within States http://www.vlrc.org/articles/44.html
Are Federal Land Acquisition Procedures Constitutional? http://www.citizensalliance.org/links/pages/articles/Wheres%20the%20Authority%20to%20Acquire%20Land.htm
The Big Lie: Federal ownership of public lands http://proliberty.com/observer/20010802.htm
The federal government is using different clause(s) within the Constitution, like the Commerce Clause as the basis for environmental laws (like the Endangered Species Act on state and private land, or other EPA laws), this raises a constitutional conflict issue, the federal government cannot use one provision of the Constitution to circumvent or destroy another. In other words, Congress cannot use a grant of power in one clause of the Constitution to get around a restraint or qualification of power in another clause.
The federal government does not have the constitutional authority to evade or defeat the limitations enumerated in Enclave Clause of the U.S. Constitution, Article I, section 8, clause 17.