Libertarian philanthropist David Koch is backing a federal challenge to same sex marriage bans, signing on to a Supreme Court brief urging the court to overturn state-level prohibitions on the practice.

He will join hundreds of other prominent right-of-center thinkers, activists, and public figures in asking the Supreme Court to prohibit states from outlawing the practice under the 14th Amendment.

Koch, the vice president of Koch Industries and the world’s sixth wealthiest person, is a deep-pocketed donor to Republican and conservative groups.

Koch Industries general counsel Mark Holden confirmed on Tuesday that Koch will sign his name to the brief. Holden said he did so in his personal capacity.

"I believe in gay marriage," he told Politico in 2012. A former vice presidential candidate on the Libertarian Party ticket, Koch is in line with that movement’s thinking on the issue, despite his support for a party that frequently opposes gay marriage.

"I think the Republican Party has a great chance of being successful and that’s why I support it … but I believe in the libertarian principles," he told Politico.

The Washington Post’s Jennifer Rubin on Tuesday reported some of the brief’s other signatories, and on the argument they’re presenting: