Halstead was willing to take him on permanently at an increased salary if he would give up the law, but Taft declined. In October 1880, Taft was appointed assistant prosecutor for Hamilton County (where Cincinnati is located), and took office the following January. Taft served for a year as assistant prosecutor, trying his share of routine cases.[10] He resigned in January 1882 after President Chester A. Arthur appointed him Collector of Internal Revenue for Ohio's First District, an area centered on Cincinnati.[11] Taft refused to dismiss competent employees who were politically out of favor, and resigned effective in March 1883, writing to Arthur that he wished to begin private practice in Cincinnati.[12] In 1884, Taft campaigned for the Republican candidate for president, Maine Senator James G. Blaine, who lost to New York Governor Grover Cleveland.[13]
In 1887, Taft, then aged 29, was appointed to a vacancy on the Superior Court of Cincinnati by Governor Joseph B. Foraker. 