Farmers on the proposed route likely wouldn’t face these threats were it not for the 2005 case Kelo v. City of New London in which the Supreme Court, divided 5-4, ruled that eminent domain powers extend to the transfer of land from one private owner to another, if that action increases economic development.

I wrote about Kelo back on TPM.

Obama supports TransCanada's bid to push ahead with part of oil pipeline
White House welcomes construction of portion of pipeline between Oklahoma and Texas, but activists condemn 'betrayal'

By Suzanne Goldenberg, US environment correspondent, guardian.co.uk, 27 Feb 2012

Barack Obama helped put the Keystone XL tar sands pipeline back on track on Monday, endorsing construction on a key southern portion of the controversial project.

The White House support for construction of a southern portion of the pipeline, running from Cushing, Oklahoma to Port Arthur, Texas, essentially unravels its rejection of the entire project just one month ago.

The move was seen by environmental campaigners as a betrayal. The Sierra Club described the revival of the pipeline project as a "dirty trick".

But the manoeuvre could insulate Obama in an election year from what was emerging as a key line in Republican attacks [....]

Also see:

Obama welcomes TransCanada plan for new pipeline
AP, Feb 27, 2012

Boehner: Obama ‘Can’t Have it Both Ways’ on Keystone Pipeline
By Jake Tapper, ABC News, Feb 27, 2012 5:16pm