for the Indianapolis Journal, recording Indiana Supreme Court decisions, and gained a good reputation with the court. He served as the city attorney from 1851 until 1853, having run for office as a Democrat. In 1853 he was appointed to a vacant reporter seat for the Supreme Court. He was elected to the position in 1854 by a strong majority and served until 1856. That year, he became embroiled in the ongoing political feud between the pro-slavery and anti-slavery factions of the state Democratic party. The pro-slavery faction won, and Porter was among the anti-slavery men expelled from the party, causing him to join the newly formed Republican Party. With his brother-in-law's help, Porter began to organize the Marion County Republican Party, and ran for the city council on the Republican ticket. He served a partial term in the office but resigned in 1859 after having won the 1858 congressional election. Congressman He served in the United States House of Representatives until 1863, having been reelected once. As a congressman during the American Civil War, he supported much of the wartime legislation. His primary contribution was his own investigation of the railroads, which had accepted numerous land grants from the government during the war and the years leading up to it. He calculated the value of the transactions, and balanced it again the amount the railroads were demanding for payment for shipping men and munitions, saving the at time cash-strapped government several million dollars. He was nominated a third time to run for Congress in 1862, but declined primarily because of the position's poor salary and his need to replenish his savings. He returned to Indianapolis, where he became head of one of the state's leading law firms; his most famous partner was future United States President Benjamin Harrison. He took on several high-profile cases, including the Ex parte Milligan case, which ended before the United States Supreme Court, who ruled that Lambdin P. Milligan, who had been arrested during the war for subversive activities, and tried and convicted by a military tribunal, should be released as the tribunal had no authority to prosecute so long as the civil courts were still in operation. He was nominated as a Republican candidate to run for governor in 1876, but he declined. In 1878, Porter was appointed by President Rutherford B. Hayes as Comptroller of the United States Treasury. As Comptroller he