He resumed the practice of law in Spokane, Washington in 1888 and was also interested in mining. He was a member of the Territorial Convention in 1889 that framed the first Washington Constitution, the state constitution of Washington, which had recently been admitted to the Union. He was an unsuccessful candidate for election as a Republican to the U.S. Senate in 1889 and 1893; he was elected on a fusion ticket with Silver Republicans, Democrats, and Populists support to the U.S. Senate and served from March 4, 1897, to March 3, 1903; he lost re-election[1] and resumed the practice of law in Spokane.
In 1903, he was a member of the Alaska Boundary Tribunal and was an unsuccessful Democratic candidate for governor in 1904. He was counsel for the United States at The Hague in the northeastern fisheries arbitration with Great Britain in 1910, and was appointed by President William H. Taft as a member of the International Joint Commission, created to prevent disputes regarding the use of boundary waters between the United States and Canada from 1911 to 1914. He was counsel for the United States before the International Joint Commission from 1918 to 1924 and practiced law in Spokane. He died there in 1932 and is interred at Greenwood Cemetery.[2]
Mount Turner on the Alaska-British Columbia border was named for him.