Hall did not return to Richmond in June and risked charges of treason for doing so. Later in 1861, Hall attended the Wheeling Convention, which re-organized a state government loyal to the United States—the future state of West Virginia. Hall attended the constitutional convention that produced the first West Virginia Constitution, and was one of four delegates to the convention selected to present the document to Congress.
Hall was elected to a two-year term as West Virginia Attorney General for the term beginning January 1, 1865. In October 1865, Hall was elected judge of the Tenth Circuit and resigned as Attorney General in December. He was re-elected a circuit judge of the Sixth Circuit (formerly the Tenth) but declined to accept.
In March 1870, GovernorWilliam E. Stevenson appointed Hall to be a member of the commission to negotiate the debt between Virginia and West Virginia. In September 1870, Hall was appointed to fill a vacancy as circuit judge in the Sixth Circuit. In October 1872, he resigned as Judge and moved to California. In 1875, he resumed the practice of law. Hall was an attorney in Santa Barbara until his death.