He graduated from Augustana College in Rock Island, Illinois with a bachelor's degree in speech communication.
Duffy became a board member of the National Federation of Independent Businesses Leadership Council (NFIB) of Illinois and became the Chairman of the Lake and Cook County Area Action Council for independent businesses.
[5] Duffy was elected to the Illinois Senate in 2008 defeating then-Round Lake Mayor Bill Gentes by sixteen points in what was originally seen to be a competitive race.
[3] As a member of the Senate, Duffy was a co-sponsor of the bill that abolished the death penalty in Illinois.
[8] Duffy resigned from the Illinois Senate on April 3, 2016 in order to take the position of president and CEO of Prevent Childhood Abuse America.