He served as judge of the circuit court of the third judicial district from January 1854 until October 1859, when he resigned.

Niblack was elected as a Democrat to the Thirty-fifth Congress to fill the vacancy caused by the death of James Lockhart.

He was again a member of the Indiana House of Representatives in 1862 and 1863, and served as delegate to the Democratic National Conventions in 1864, 1868, and 1876.

He resumed the practice of law and served as judge of the Indiana Supreme Court 1877−1889.

This article incorporates public domain material from the Biographical Directory of the United States Congress