Mark S. Massa (born March 6, 1961) is an American lawyer who has served as an associate justice of the Indiana Supreme Court since April 2, 2012, when he succeeded Justice Randall T. Shepard.^[1][2]

Born in Milwaukee, Wisconsin, Massa moved to Indiana in 1979 to attend Indiana University, from which he received a Bachelor of Arts in Journalism in 1983. Massa interned at the South Bend Tribune and Milwaukee Journal Sentinel before becoming a sportswriter for the Evansville Courier & Press, where he also covered the courts and local government.^[3]

In 1985, he became a deputy press secretary and speechwriter for Governor Robert D. Orr.^[3] He then attended the evening division of Indiana University Robert H. McKinney School of Law, and was a law clerk for Indiana Supreme Court Chief Justice Randall Shepard from 1991 to 1993.^[4][3]

Massa joined the Marion County Prosecutor’s Office in Indianapolis. After serving as a deputy prosecutor for 15 years, including seven years as chief counsel to Prosecutor Scott Newman. Massa was an assistant United States attorney in the Southern District of Indiana, where he earned the Inspector General's Integrity Award from the Department of Health and Human Services. He served as general counsel to Governor Mitch Daniels, chaired the Alcohol and Tobacco Commission, served on the Indianapolis Marion County Police Merit Board, and was executive director of the Indiana Criminal Justice Institute prior to his appointment to the supreme court.^[3]

In March 2012, Governor Mitch Daniels appointed Massa to the Indiana Supreme Court.^[4][3]

In 2018, Massa authored an opinion of the court holding that Indiana's shoreline on Lake Michigan was open to all, barring adjacent property owners from excluding others from such land.^[5]