Born in Jackson, Michigan, Coats graduated from Wheaton College in Illinois and the Indiana University School of Law – Indianapolis. He served in the U.S. Army from 1966 to 1968. Coats represented Indiana's 4th congressional district in the United States House of Representatives from 1981 to 1989. He was appointed to fill the Senate seat vacated by Dan Quayle following Quayle's election as Vice President of the United States. Coats won the 1990 special election to serve the remainder of Quayle's unexpired term, as well as the 1992 election for a full six-year term. He did not seek reelection in 1998 and was succeeded by Democrat Evan Bayh.