[1][2] A Democrat, Hanna first became involved in Indiana politics after he was appointed Governor James Whitcomb's personal secretary.
[1][2] After leaving the state senate, Hanna moved to Terre Haute in 1854 to set up a private law practice.
He left the position in 1857, when he was appointed to the Indiana Supreme Court on December 10, 1857, by Governor Ashbel P. Willard to succeed the retiring Justice Samuel Gookins.
Board of Commissioners of Sinking Fund v. Ristine, one of two cases concerning whether Indiana State Auditor Joseph Ristine had the right to refuse orders from Governor Oliver P. Morton to make an interest payment on the state debt in lieu of the General Assembly approving appropriations measures before adjourning.
In 1864, Hanna and other Democratic justices on the Supreme Court lost their races for re-election following an electoral sweep by Governor Morton and state Republicans.