On MSNBC's Morning Joe, no less, Huckabee explains his legal stance in supporting Kim Davis. Basically because the US Supreme Court's ruling on gay marriage has usurped the Constitution and Kentucky law.

"You would have hated Lincoln..."
"Jefferson warned..."
"...cannot over-rule the Laws of Nature and of Nature's God..." [a line from the Declaration of Independence]
"The interpretation of 5 unelected lawyers..." [referring to the 5 of 9 justices of the U.S.S.C. who ruled in favor of gay marriage, two of whom have personally conducted gay marriages and should have recused themselves from the gay marriage ruling!]
"Tell me the specific law..."

Over and over, Huckabee cites the founders and their original intent, and actions by presidents such as Jefferson and Lincoln that are consistent with actions by Kim Davis in her resistance of an unjust law.
As Huckabee simultaneously asks for the specific law in the Constitution or elsewhere that compels Kentucky to recognize gay marriage. He cites the precedent to support his own position, while citing the lack of precedent for the Supreme Court's ruling on gay marriage, that he and Kim Davis have every right and precedent to resist.