Are the Koch brothers principled libertarians, as Radley Balko argued in a piece pointing out their large donation to the American Civil Liberties Union? The conclusion drawn by Adam Serwer is that they're earnest in their beliefs but inclined to privilege economic liberty whenever it comes into conflict with other sorts:
The best example of this I can think of is the Senate's lost liberaltarian Russ Feingold. Feingold was the only senator to vote against the PATRIOT Act. He was one of the first senators to endorse marriage equality. He voted against the war in Iraq, against TARP and financial reform, and has consistently sought to rein in the surveillance state. He was, however, also one of the architects of campaign-finance reform along with John McCain and a supporter of the health-care bill and the stimulus.
When Feingold's candidacy was in danger, the Koch's poured their money into the coffers of Feingold's opponent, Ron Johnson... All in all, the Koch family gave Johnson more than $25,000 to send Russ Feingold home. What type of candidate were they supporting? Johnson is anti-marriage equality, anti-choice, has no problem with open-ended military engagements and he supports the PATRIOT Act with some caveats, but only because "you have Barack Obama in power versus George Bush. I wasn't overly concerned with George Bush in power." In other words, faced with one candidate who shares their views on social issues and national security and another who shares their views on economic issues, the Kochs chose the latter.
It's a choice made by a lot of folks on the right.