She has served as president of the State Bar of Montana, on numerous state and federal justice committees and a number of social services boards. Sheehy graduated from UM in 1985 with a bachelor's degree in history with honors and from UM Law School in 1988 as first in her class. She has practiced law in Billings since 1988, the last 15 years at her own Sheehy Law Firm. She has had a focus on constitutional law, contract issues, insurance law and media law, including representing the Billings Gazette and Bozeman, Chronicle in right-to-know cases. She also served on the boards of the Billings YMCA and Youth Dynamics.