[2] He was first elected as district attorney of Middlesex County, Massachusetts in 1982, defeating incumbent DA John Droney in the Democratic primary.

In 1990, he was elected attorney general of Massachusetts, defeating incumbent James Shannon in the Democratic primary.

[5] Afterwards, Harshbarger served as president of the public interest organization Common Cause for three years, where he supported efforts to pass the Bipartisan Campaign Reform Act.

Prior to joining Casner & Edwards, Harshbarger was senior counsel at Proskauer Rose LLP[8] in Boston, MA.

Harshbarger has continued to serve the Commonwealth of Massachusetts as a private practice attorney by accepting appointments by both Republican and Democratic Governors of MA .