Since leaving office, Simpson has practiced law and taught at different universities. He also served on the Continuity of Government Commission, the American Battle Monuments Commission, and the Iraq Study Group. In 2010, President Barack Obama appointed him to co-chair the National Commission on Fiscal Responsibility and Reform, which made several recommendations on ways to reduce the national debt. He has been a vocal proponent of amending the U.S. Constitution to overturn Citizens United v. FEC (2010) and allow Congress to set reasonable limits on campaign spending in U.S. elections.
