She is from Castletroy in County Limerick. A member of Limerick County Council for the Castleconnell local electoral area since 1985, Jackman has unsuccessfully contested four general elections in the Limerick East constituency (1989, 1992, 1997, and 2002), falling just 305 votes short of winning seat at the 1997 general election. She was also defeated at the Limerick East by-election in March 1998, and did not stand at the 2007 general election.
After her 1989 defeat, she was elected to the 19th Seanad on the Labour Panel. She lost her seat at the 1993 Seanad elections, but was re-elected in 1997 to the 21st Seanad. At the 2002 Seanad elections, she stood instead on the Industrial and Commercial Panel, but did not win a seat.
- "Ms. Mary Jackman". Oireachtas Members Database. Retrieved 15 February 2008.
- "Mary Jackman". ElectionsIreland.org. Retrieved 15 February 2008.