In Congress, Buyer served as one of the House managers (prosecutors) in the impeachment trial of President Bill Clinton in 1999.

On January 29, 2010, Buyer announced he would not seek a tenth term to the House to spend more time with his wife, who has an incurable autoimmune disease.

His first civilian job, from 1987 to 1998, was as an Indiana state deputy attorney general; he then started his own private law practice.

During the Gulf War (1990–1991), Buyer, then a captain, spent five months on active duty giving legal counsel to commanders and interrogating Iraqi P.O.W.s.

Pending further orders, I request immediate indefinite leave of the United States House of Representatives to accommodate my military duties."

He also said that "a need was identified, of which Congressman Buyer has the unique skill and experience to meet the requirements," to serve in Iraq.

Thus in June 2003, the Indianapolis Star reported that the Army, in a March 31 letter to Buyer signed by Army secretary Thomas White, had rejected Buyer's offer to serve in the Iraq War, because "we are able to meet the need without your participation" and "we are concerned that your presence would put in jeopardy the safety of those serving around you."

[7] In April 2004, Buyer was promoted to colonel in the United States Army Reserve[9] by President George W. Bush in the Oval Office.

[10] In his 1992 campaign, Buyer supported bringing to a vote on the House floor a Congressional amendment for term limits on members of Congress.

[11] Buyer, who interrogated captured Iraqis during the Gulf War, voted against the Detainee Treatment Act of 2005, specifically the no torture amendment offered by Senator John McCain.

[14] When Buyer first ran for Congress in 1992, he faced three-term Democratic incumbent Jim Jontz in what was then the 5th District, comprising twenty primarily rural counties in north central Indiana.

[23] In recent years, his largest corporate donors have included Eli Lilly and Company, AT&T Inc. and Reynolds American.

As of October 2009, the foundation had not awarded any scholarships, and had given out only $10,500 in charitable grants, almost half of which went to a cancer fund run by the chief Washington lobbyist for Eli Lilly and Company.

In March 2018, Buyer attended a golf outing with a T-Mobile executive, from whom he learned about the company's then nonpublic plan to acquire Sprint.

In a parallel action, the U.S. Attorney's Office for the Southern District of New York announced related criminal charges.

[33][34] At the trial, Karen Hensel, a television reporter, told the jury that Buyer traded stocks for her to help her "catch up" financially after they had an affair.

[2] In 2008, in Golf Digest's list of the top 200 golfers among political power brokers in Washington, Buyer was ranked 32nd, with a handicap of 5.6.

He was hired in June 2008 as a federal affairs manager for the Pharmaceutical Research and Manufacturers of America (PhRMA), a major lobbying organization in Washington, D.C., and the largest donor to the foundation.