This issue is an interesting paradox: Barack Obama and John McCain support building a border fence, Congress passed a law authorizing money and the condemnation of land.
So why will the fence never be built?
1. Funding
$3B that were oringally in the defense appropriation bill to fund the fence mysteriously disappeared in conference.
Lindsey Graham has an unusual theory as to why this was:
The amendment that I offered, supported by all my colleagues here, passed 95-1. Only in Washington would that be a mixed signal.
2. Land
It is really difficult to believe this is an issue. For better or worse, in America, like virtually every other country on Earth, the government can take your land for any reason. The only restraint is that the government has to articulate a reason, usually this is in the statute. Frequently the statute sets out some procedures for condemning (taking) the land. Here are the relevant ones for this statute.
(b) (1) The Attorney General may contract for or buy any interest in land, including temporary use rights, adjacent to or in the vicinity of an international land border when the Attorney General deems the land essential to control and guard the boundaries and borders of the United States against any violation of this Act.(2) The Attorney General may contract for or buy any interest in land identified pursuant to paragraph (1) as soon as the lawful owner of that interest fixes a price for it and the Attorney General considers that price to be reasonable.
(3) When the Attorney General and the lawful owner of an interest identified pursuant to paragraph (1) are unable to agree upon a reasonable price, the Attorney General may commence condemnation proceedings pursuant to the Act of August 1, 1888 (Chapter 728; 25 Stat. 357).
(4) The Attorney General may accept for the United States a gift of any interest in land identified pursuant to paragraph (1).
This case illustrates the futility of simple condemnation of land. Here, Baldomero is a retired migrant worker who tends to a few goats. He is completely illiterate, and only speaks Spanish. When DHS asked if they could survey the land, he told them to go away. When they came back, they couldn't speak to Baldomero because of the dogs on his property. So, the Justice Department started condemnation proceedings which Baldomero's attorney feels is inconsistent with the statute above because there were no negotiations. Unsurprisingly, Baldomero lost at trial because DHS' efforts to negotiate were frustrated by vicious dogs.
I wish I could make this stuff up.